Toyo Air Pressure Sweet Spot
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From: Siege Perilous
Toyo Air Pressure Sweet Spot
I searched and didn't see definitive answers.
With Toyo RA-1, where is the air pressure handling sweet spot?
Having used these for a couple of years, I will start out with 27-28 pounds cold, and get about 36 pounds hot. That <u>seems</u> to work, but I'm afraid I might be missing something.
What started all this was the Seat Time Friday. Mr Roush was there with his TL 6-6 and 235-40-17 Toyos. He thought he was doing fine with 45 pounds hot, but it looked to us like he was definitely melting the tyres at that pressure and that he was losing time as a result of it.
Am I right that pressures need to be a lot lower, or am I being an idiot again?
With Toyo RA-1, where is the air pressure handling sweet spot?
Having used these for a couple of years, I will start out with 27-28 pounds cold, and get about 36 pounds hot. That <u>seems</u> to work, but I'm afraid I might be missing something.
What started all this was the Seat Time Friday. Mr Roush was there with his TL 6-6 and 235-40-17 Toyos. He thought he was doing fine with 45 pounds hot, but it looked to us like he was definitely melting the tyres at that pressure and that he was losing time as a result of it.
Am I right that pressures need to be a lot lower, or am I being an idiot again?
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Joined: Jul 2003
Posts: 1,115
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From: Ottawa, Canada
Re: Toyo Air Pressure Sweet Spot (George Knighton)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by George Knighton »</TD></TR><TR><TD CLASS="quote">I searched and didn't see definitive answers.
With Toyo RA-1, where is the air pressure handling sweet spot?
Having used these for a couple of years, I will start out with 27-28 pounds cold, and get about 36 pounds hot. That <u>seems</u> to work, but I'm afraid I might be missing something.
Am I right that pressures need to be a lot lower, or am I being an idiot again?</TD></TR></TABLE>
I run my tires so that they are at 40# hot. Which means cold pressures in the 30-33 range.
With Toyo RA-1, where is the air pressure handling sweet spot?
Having used these for a couple of years, I will start out with 27-28 pounds cold, and get about 36 pounds hot. That <u>seems</u> to work, but I'm afraid I might be missing something.
Am I right that pressures need to be a lot lower, or am I being an idiot again?</TD></TR></TABLE>
I run my tires so that they are at 40# hot. Which means cold pressures in the 30-33 range.
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From: Chicago
Re: Toyo Air Pressure Sweet Spot (MightyMouseTech)
From Toyo's website:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toyo's website »</TD></TR><TR><TD CLASS="quote">
- High 30's to Low 40's (PSI)</TD></TR></TABLE>
I set mine to 30-33 cold (and usually 31-32), just like MightyMouseTech (which is consistent with Toyo's advice)...
Modified by nsxtasy at 8:10 PM 6/24/2006
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toyo's website »</TD></TR><TR><TD CLASS="quote">
- High 30's to Low 40's (PSI)</TD></TR></TABLE>I set mine to 30-33 cold (and usually 31-32), just like MightyMouseTech (which is consistent with Toyo's advice)...
Modified by nsxtasy at 8:10 PM 6/24/2006
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Joined: Jan 2003
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From: Cogito ergo sum, Canada
Re: Toyo Air Pressure Sweet Spot (George Knighton)
Here is some official Toyo info for the setup of the RA1 from the Toyo Canada web site: http://www.toyoracing.com/TireInfo/RA1_tires.asp
Best Operating Temperature:
160° to 220°F
Higher than 220°F the tire performance will start to go off, although temperatures as high as 300°F have been seen before blistering takes place.
Note: These tires should not be stored below 0° Celsius to prevent tread compound from craking.
Do not store inflated.
Camber:
Negative 2.5 to negative 5.0 deg. acceptable. Anything lower than
2.5 or higher than 5.0 deg. negative will create some irregular wear.
Castor:
As much as possible (very difficult with stock vehicles).
Tire Pressures :
Front Drive - Start no less than 24 psi.
Rear Drive - Start no less than 18 psi.
Goal - 41 to 43 psi (hot)
Air Pressures Recomendations:
Dry Conditions
Front Drive - Starting minimum 24 psi.
Rear Drive - Starting minimum 18 psi.
Goal - 41 to 43 psi (hot)
Wet: (heavy water layer)
Front Drive - Starting minimum 28-30 psi.
Rear Drive - Starting minimum 22-24 psi.
Front Drive - Starting minimum 18-20 psi.
Rear Drive - Starting minimum 12-14 psi.
Shaving Requirements :
Wet Grip Grip & Longevity Ultimate Grip
Full Depth 4/32" 2-3/32"
And this is info from Toyo Australia about shaving (buffing down under) the RA1:
Buffing (often referred to as "shaving") tyres used for motor sport has been a common practice with motor sport competitors for decades. The process of buffing removes some of the tread rubber of a tyre, reducing its tread depth.
The thought of buying a new set of tyres a then buffing 50% or more of the tread seems wasteful, until the advantages of this practice are realised. Buffing tyres is common in classes of racing where grooved tyres must be used in all conditions on tarmac. This article explains the advantages & disadvantages of buffing tyres for motor sport use on tarmac.
The Basic Concept: All things being the same, a smooth or slick tyre provides optimum performance on dry tarmac. Where grooved tyres must be used on dry tarmac, minimising the groove area will improve grip and therefore reduce lap times. Buffing tyres reduces the groove or "void" area of the tread.
Toyo Proxes RA1 with original tread depth. Toyo Proxes RA1 buffed to a tread depth of 3.0mm at tread centre & 2.5mm on the shoulder grooves.
Advantages of buffing tyres for motor sport use:
1. Reduced tread flex. Tread grooves effectively split the tread into "blocks". Cornering and braking forces cause the tread blocks to flex, which reduces the maximum amount of grip available. The smaller the tread blocks are, the less they will flex. Therefore, tread patterns with smaller tread blocks and / or greater tread depth will have more tread flex compare to tread patterns with less groove area. Tread flex also produces heat.
2. Reduced heat build-up for improved endurance. Tread-flex produces heat. In some applications this extra heat generation results in tread temperatures which are excessive, causing a reduction in grip levels. Racers often often refer to this as "going-off'. Reduced tread depths also improve the tyres' ability to dissipate heat and therefore maintain optimum temperatures (and therefore grip levels) for a longer period of time.
3. Reduced amount of inflation pressure build-up. A result of reduced heat build-up is reduced inflation pressure build-up. The more heat generated, the greater the amount of pressure build-up. Less variation in pressures produces more consistent tyre performance.
4. Slower wear rate. The reduction of tread flex and heat build-up means a much slower wear rate compared to a tyre with new tread depth ( or similar to new tread depth ) in the same using conditions.
5. Reduced amount of irregular wear. The reduction of tread flex, especially on the tread shoulders, reduces the severity of feathering of the tread blocks.
6. Faster dry lap times. This is the ultimate reason for buffing tyres.
Disadvantages of buffing tyres for motor sport use:
1. Cost. Buffing of tyres attracts extra charges.
2. Diminished wet track performance. While improving dry lap times, buffing tyres makes them unsuitable for use on wet tracks where there is standing water. Buffed tread depths makes tyres susceptible to aquaplaning. Tyres with new tread depth or close to new tread depth will provide optimum performance on tarmac where there is standing water.
Buffing of non-motor sport tyre tyres:
Buffing non-motor sport type tyres will improve their performance on dry tarmac for users who want improve tyre performance for "track days", with the same advantages & disadvantages as buffing motor sport tyres.
Degree of improved dry track performance from buffing:
This depends on the amount of groove area or void the tread pattern has with original tread depth. The more groove area a tyre has, the greater the improvement in dry track performance provided by buffing. There is minimal gains to be made by buffing some motor sport tyres that have minimal tread grooves.
Prepared by Steve Burke, Tyre Technical Department.
Unshaved RA1's are a waste of time in my experience.
Best Operating Temperature:
160° to 220°F
Higher than 220°F the tire performance will start to go off, although temperatures as high as 300°F have been seen before blistering takes place.
Note: These tires should not be stored below 0° Celsius to prevent tread compound from craking.
Do not store inflated.
Camber:
Negative 2.5 to negative 5.0 deg. acceptable. Anything lower than
2.5 or higher than 5.0 deg. negative will create some irregular wear.
Castor:
As much as possible (very difficult with stock vehicles).
Tire Pressures :
Front Drive - Start no less than 24 psi.
Rear Drive - Start no less than 18 psi.
Goal - 41 to 43 psi (hot)
Air Pressures Recomendations:
Dry Conditions
Front Drive - Starting minimum 24 psi.
Rear Drive - Starting minimum 18 psi.
Goal - 41 to 43 psi (hot)
Wet: (heavy water layer)
Front Drive - Starting minimum 28-30 psi.
Rear Drive - Starting minimum 22-24 psi.
Front Drive - Starting minimum 18-20 psi.
Rear Drive - Starting minimum 12-14 psi.
Shaving Requirements :
Wet Grip Grip & Longevity Ultimate Grip
Full Depth 4/32" 2-3/32"
And this is info from Toyo Australia about shaving (buffing down under) the RA1:
Buffing (often referred to as "shaving") tyres used for motor sport has been a common practice with motor sport competitors for decades. The process of buffing removes some of the tread rubber of a tyre, reducing its tread depth.
The thought of buying a new set of tyres a then buffing 50% or more of the tread seems wasteful, until the advantages of this practice are realised. Buffing tyres is common in classes of racing where grooved tyres must be used in all conditions on tarmac. This article explains the advantages & disadvantages of buffing tyres for motor sport use on tarmac.
The Basic Concept: All things being the same, a smooth or slick tyre provides optimum performance on dry tarmac. Where grooved tyres must be used on dry tarmac, minimising the groove area will improve grip and therefore reduce lap times. Buffing tyres reduces the groove or "void" area of the tread.
Toyo Proxes RA1 with original tread depth. Toyo Proxes RA1 buffed to a tread depth of 3.0mm at tread centre & 2.5mm on the shoulder grooves.
Advantages of buffing tyres for motor sport use:
1. Reduced tread flex. Tread grooves effectively split the tread into "blocks". Cornering and braking forces cause the tread blocks to flex, which reduces the maximum amount of grip available. The smaller the tread blocks are, the less they will flex. Therefore, tread patterns with smaller tread blocks and / or greater tread depth will have more tread flex compare to tread patterns with less groove area. Tread flex also produces heat.
2. Reduced heat build-up for improved endurance. Tread-flex produces heat. In some applications this extra heat generation results in tread temperatures which are excessive, causing a reduction in grip levels. Racers often often refer to this as "going-off'. Reduced tread depths also improve the tyres' ability to dissipate heat and therefore maintain optimum temperatures (and therefore grip levels) for a longer period of time.
3. Reduced amount of inflation pressure build-up. A result of reduced heat build-up is reduced inflation pressure build-up. The more heat generated, the greater the amount of pressure build-up. Less variation in pressures produces more consistent tyre performance.
4. Slower wear rate. The reduction of tread flex and heat build-up means a much slower wear rate compared to a tyre with new tread depth ( or similar to new tread depth ) in the same using conditions.
5. Reduced amount of irregular wear. The reduction of tread flex, especially on the tread shoulders, reduces the severity of feathering of the tread blocks.
6. Faster dry lap times. This is the ultimate reason for buffing tyres.
Disadvantages of buffing tyres for motor sport use:
1. Cost. Buffing of tyres attracts extra charges.
2. Diminished wet track performance. While improving dry lap times, buffing tyres makes them unsuitable for use on wet tracks where there is standing water. Buffed tread depths makes tyres susceptible to aquaplaning. Tyres with new tread depth or close to new tread depth will provide optimum performance on tarmac where there is standing water.
Buffing of non-motor sport tyre tyres:
Buffing non-motor sport type tyres will improve their performance on dry tarmac for users who want improve tyre performance for "track days", with the same advantages & disadvantages as buffing motor sport tyres.
Degree of improved dry track performance from buffing:
This depends on the amount of groove area or void the tread pattern has with original tread depth. The more groove area a tyre has, the greater the improvement in dry track performance provided by buffing. There is minimal gains to be made by buffing some motor sport tyres that have minimal tread grooves.
Prepared by Steve Burke, Tyre Technical Department.
Unshaved RA1's are a waste of time in my experience.
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Joined: Jan 2000
Posts: 23,478
Likes: 2
From: Chicago
Re: Toyo Air Pressure Sweet Spot (descartesfool)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">Unshaved RA1's are a waste of time in my experience.</TD></TR></TABLE>
If anyone would like to throw some of that "waste of time" my way, I'll take 'em.
That's how I use mine (but I'm willing to trade off a wee bit of grip for longer treadlife and lower cost)...
If anyone would like to throw some of that "waste of time" my way, I'll take 'em.
That's how I use mine (but I'm willing to trade off a wee bit of grip for longer treadlife and lower cost)...
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Joined: Jan 2003
Posts: 1,979
Likes: 0
From: Cogito ergo sum, Canada
Re: Toyo Air Pressure Sweet Spot (George Knighton)
Here is some additional info I had saved from Toyo Australia:
USING NITROGEN COMPARED TO COMPRESSED AIR FOR TYRE INFLATION
Nitrogen behaves quite differently compared to normal compressed when used to inflate tyres. When subjected to heat, compressed air will expand at a greater rate compared to nitrogen. For this reason, all factors being equal, there will be less pressure build-up when nitrogen is used for tyre inflation compared to normal compressed air. For this reason cold inflation pressures should be higher when using nitrogen inflation compared to using compressed air.
The advantage of using nitrogen compared to compressed air is that cold inflation pressures are closer to optimum hot pressures. Steering feel and response will be superior with the higher inflation pressures for the first 2 - 3 laps compared to using the lower inflation pressures suitable when using normal compressed air. Nitrogen inflation also provides less variance in inflation pressures, therefore more consistent tyre performance and steering response. For more information regarding nitrogen inflation, please refer to the technical article "Inflating tyres with nitrogen compared to compressed air".
A good "rule of thumb" to determine the optimum cold inflation pressures for nitrogen inflation: 1. determine the usual amount of pressure build-up that occurs using compressed air, 2. halve that amount, and 3. add the amount from step 2 to the cold inflation pressure used for compressed air.
NOTE: When using nitrogen for tyre inflation, ensure tyres are purged of compressed air and moisture, otherwise the advantages of nitrogen inflation will not be realised.
WET CONDITIONS & INFLATION PRESSURES
For wet tracks (STANDING WATER) increase pressures by 4-8 psi compared to dry track pressures. Increasing the pressure for wet tracks makes the tyre's contact patch smaller, making the tyre less susceptible to aquaplaning.
There is less heat build-up on wet tracks, therefore less pressure build-up. This is another reason cold inflation pressures need to be higher than those used for dry conditions.
For optimum performance on tracks where there is standing water, tyres with new depth or close to new tread depth will provide optimum performance. Buffed or worn tyres (3 - 1.5mm tread depth) will be susceptible to aquaplaning where there is standing water.
It is recommended that tyres used on wet or damp tracks are given a short "scrubbing-in" session before they are used competitively to remove the layer of mould release on the new tyres. Without "scrubbing-in" the tyres will be slippery until this layer of mould release agent is worn away.
Camber Settings
Toyo motor sport radials will provide optimum cornering grip with camber settings between negative 3 and 6 degrees on steer axles. Where adjustment is possible, negative camber on drive axles will also improve cornering grip. Optimum camber angles will provide optimum cornering grip, and therefore will be an important contributing factor for improving lap times.
NOTE: On some vehicles a lack of negative camber can over-heat the outside tread shoulder causing grip levels to drop-off suddenly and in some cases cause blistering of the outside tread shoulder. Large heavy, front engine cars are most susceptible to this type of tyre damage.
CAMBER SETTINGS & INFLATION PRESSURES
Where camber adjustment is limited or class rules limit the amount of negative camber allowed, increasing cold inflation pressures is necessary to prevent the outside tread shoulder overheating. This also applies to vehicles that are used on the street as well as the track, where the camber settings are a compromise for this dual purpose. Where this is the case, adding 3 - 6psi to recommended cold and hot inflation pressures usually prevents the outside tread shoulder over-heating.
Hot Inflation Pressures
Hot inflation pressures indicate the suitability of the cold inflation pressures. Where hot pressures are too low, start with a higher cold inflation pressure or vice-versa. Pressures shown below are for inflation with compressed air.
Vehicle Weight Optimum Hot Inflation Pressures
Very Light < 800kg 26 - 32 psi
Light 800kg - 1000kg 30 - 36 psi
Heavy 1000 - 1400kg 34 - 40 psi
Very Heavy > 1400kg 38 - 45 psi
NOTE: Tyres with full tread depths used on dry tracks will have more tread flex and therefore more heat build-up compared to tyres with reduced tread depths. One result of this heat build-up is increased pressure build-up. The amount of pressure build-up will decrease as tread depth decreases.
Tread Depths & Tyre Performance on wet & dry surfaces
All grooved motor sport tyres will have some tread flex. On dry surfaces tread flex reduces overall grip levels and therefore lap times. To optimise dry grip levels with grooved race tyres, tread flex needs to be minimised. The more groove area or "void" a tread pattern has, the greater the amount of tread flex there will be in dry conditions.
PROXES RA1 & TRAMPIO R1R - These 2 patterns have tread depths of 6mm or >6mm when new and have enough groove area to be very effective as "wets" with new tread depths or close to new tread depths. For optimum dry track performance, buffing will make a large difference in grip and endurance for these two patterns and is highly recommended. Buffing will also provide more even tread wear and a slower wear rate.
PROXES & TRAMPIO R888 - These 2 identical patterns have 5mm of tread depth when new and minimal groove area for optimum dry track performance. Buffing these two patterns will provide a small improvement for cornering grip on dry tracks.
Tread Temperatures
As for most motor sport tyres, Toyo motor sport radials can be slippery when cold. Caution needs to be exercised until the tyres have had some time to warm-up. Grip levels will be low when the tread temperature is less than 60 degrees Celsius.
Optimum operating temperatures for Toyo motor sport radials is between 75 and 100 degrees Celsius. Over 100 degrees Celsius, grip levels drop-off rapidly.
Rim widths and tyre performance
Toyo motor sport radials will provide optimum performance where the rim size allows the sidewall to have little or no protrusion from the rim flange.
Each Toyo motor sport radial product information page includes a link to download a PDF file that quotes dimensional information, including approved rim widths. Where possible, use of minimum rim widths should be avoided. For most sizes, optimum tyre performance will be provided with rim widths that are from the mid point to the maximum in the range of approved rim widths shown.
Street use
All three Toyo motor sport radial patterns are legal for use on public roads but recommended for competition or use on closed circuits. Grooved, street legal race tyres are designed for users who need to drive their vehicle to and from the circuit, and / or where the class regulations specify that street legal tyres must be used.
When compared to high performance or ultra-high performance tyres, when used on public roads, Toyo motor sport radials will:
1. have comparatively poor ride comfort. Toyo motor sport radials have a steel sidewall ply to minimise sidewall deflection for optimum cornering grip.
2. be susceptible to "tram-lining" / "tracking". The casing stiffness provided by the steel sidewall ply and wide belt packages used on Toyo motor sport radials make them susceptible to tram-lining caused by road irregularities common on public roads.
3. have faster tread wear. The tread compounds used on Toyo motor sport radials provide much higher grip levels compared to high performance or ultra-high performance tyres rather than long tread life.
4. be slippery when cold. Due to the tread compounds & construction types, grip levels will be low until the tyres have had some warming-up. This will be especially noticeable in cold and / or rainy conditions.
5. be susceptible to aquaplaning when used with low tread depths (3 -1.5mm) on wet roads, especially in heavy rain conditions. Users need to exercise caution in these conditions with careful monitoring of vehicle speed to avoid aquaplaning.
Based on the recommendations, I would say at 36 psi, you are a little low.
USING NITROGEN COMPARED TO COMPRESSED AIR FOR TYRE INFLATION
Nitrogen behaves quite differently compared to normal compressed when used to inflate tyres. When subjected to heat, compressed air will expand at a greater rate compared to nitrogen. For this reason, all factors being equal, there will be less pressure build-up when nitrogen is used for tyre inflation compared to normal compressed air. For this reason cold inflation pressures should be higher when using nitrogen inflation compared to using compressed air.
The advantage of using nitrogen compared to compressed air is that cold inflation pressures are closer to optimum hot pressures. Steering feel and response will be superior with the higher inflation pressures for the first 2 - 3 laps compared to using the lower inflation pressures suitable when using normal compressed air. Nitrogen inflation also provides less variance in inflation pressures, therefore more consistent tyre performance and steering response. For more information regarding nitrogen inflation, please refer to the technical article "Inflating tyres with nitrogen compared to compressed air".
A good "rule of thumb" to determine the optimum cold inflation pressures for nitrogen inflation: 1. determine the usual amount of pressure build-up that occurs using compressed air, 2. halve that amount, and 3. add the amount from step 2 to the cold inflation pressure used for compressed air.
NOTE: When using nitrogen for tyre inflation, ensure tyres are purged of compressed air and moisture, otherwise the advantages of nitrogen inflation will not be realised.
WET CONDITIONS & INFLATION PRESSURES
For wet tracks (STANDING WATER) increase pressures by 4-8 psi compared to dry track pressures. Increasing the pressure for wet tracks makes the tyre's contact patch smaller, making the tyre less susceptible to aquaplaning.
There is less heat build-up on wet tracks, therefore less pressure build-up. This is another reason cold inflation pressures need to be higher than those used for dry conditions.
For optimum performance on tracks where there is standing water, tyres with new depth or close to new tread depth will provide optimum performance. Buffed or worn tyres (3 - 1.5mm tread depth) will be susceptible to aquaplaning where there is standing water.
It is recommended that tyres used on wet or damp tracks are given a short "scrubbing-in" session before they are used competitively to remove the layer of mould release on the new tyres. Without "scrubbing-in" the tyres will be slippery until this layer of mould release agent is worn away.
Camber Settings
Toyo motor sport radials will provide optimum cornering grip with camber settings between negative 3 and 6 degrees on steer axles. Where adjustment is possible, negative camber on drive axles will also improve cornering grip. Optimum camber angles will provide optimum cornering grip, and therefore will be an important contributing factor for improving lap times.
NOTE: On some vehicles a lack of negative camber can over-heat the outside tread shoulder causing grip levels to drop-off suddenly and in some cases cause blistering of the outside tread shoulder. Large heavy, front engine cars are most susceptible to this type of tyre damage.
CAMBER SETTINGS & INFLATION PRESSURES
Where camber adjustment is limited or class rules limit the amount of negative camber allowed, increasing cold inflation pressures is necessary to prevent the outside tread shoulder overheating. This also applies to vehicles that are used on the street as well as the track, where the camber settings are a compromise for this dual purpose. Where this is the case, adding 3 - 6psi to recommended cold and hot inflation pressures usually prevents the outside tread shoulder over-heating.
Hot Inflation Pressures
Hot inflation pressures indicate the suitability of the cold inflation pressures. Where hot pressures are too low, start with a higher cold inflation pressure or vice-versa. Pressures shown below are for inflation with compressed air.
Vehicle Weight Optimum Hot Inflation Pressures
Very Light < 800kg 26 - 32 psi
Light 800kg - 1000kg 30 - 36 psi
Heavy 1000 - 1400kg 34 - 40 psi
Very Heavy > 1400kg 38 - 45 psi
NOTE: Tyres with full tread depths used on dry tracks will have more tread flex and therefore more heat build-up compared to tyres with reduced tread depths. One result of this heat build-up is increased pressure build-up. The amount of pressure build-up will decrease as tread depth decreases.
Tread Depths & Tyre Performance on wet & dry surfaces
All grooved motor sport tyres will have some tread flex. On dry surfaces tread flex reduces overall grip levels and therefore lap times. To optimise dry grip levels with grooved race tyres, tread flex needs to be minimised. The more groove area or "void" a tread pattern has, the greater the amount of tread flex there will be in dry conditions.
PROXES RA1 & TRAMPIO R1R - These 2 patterns have tread depths of 6mm or >6mm when new and have enough groove area to be very effective as "wets" with new tread depths or close to new tread depths. For optimum dry track performance, buffing will make a large difference in grip and endurance for these two patterns and is highly recommended. Buffing will also provide more even tread wear and a slower wear rate.
PROXES & TRAMPIO R888 - These 2 identical patterns have 5mm of tread depth when new and minimal groove area for optimum dry track performance. Buffing these two patterns will provide a small improvement for cornering grip on dry tracks.
Tread Temperatures
As for most motor sport tyres, Toyo motor sport radials can be slippery when cold. Caution needs to be exercised until the tyres have had some time to warm-up. Grip levels will be low when the tread temperature is less than 60 degrees Celsius.
Optimum operating temperatures for Toyo motor sport radials is between 75 and 100 degrees Celsius. Over 100 degrees Celsius, grip levels drop-off rapidly.
Rim widths and tyre performance
Toyo motor sport radials will provide optimum performance where the rim size allows the sidewall to have little or no protrusion from the rim flange.
Each Toyo motor sport radial product information page includes a link to download a PDF file that quotes dimensional information, including approved rim widths. Where possible, use of minimum rim widths should be avoided. For most sizes, optimum tyre performance will be provided with rim widths that are from the mid point to the maximum in the range of approved rim widths shown.
Street use
All three Toyo motor sport radial patterns are legal for use on public roads but recommended for competition or use on closed circuits. Grooved, street legal race tyres are designed for users who need to drive their vehicle to and from the circuit, and / or where the class regulations specify that street legal tyres must be used.
When compared to high performance or ultra-high performance tyres, when used on public roads, Toyo motor sport radials will:
1. have comparatively poor ride comfort. Toyo motor sport radials have a steel sidewall ply to minimise sidewall deflection for optimum cornering grip.
2. be susceptible to "tram-lining" / "tracking". The casing stiffness provided by the steel sidewall ply and wide belt packages used on Toyo motor sport radials make them susceptible to tram-lining caused by road irregularities common on public roads.
3. have faster tread wear. The tread compounds used on Toyo motor sport radials provide much higher grip levels compared to high performance or ultra-high performance tyres rather than long tread life.
4. be slippery when cold. Due to the tread compounds & construction types, grip levels will be low until the tyres have had some warming-up. This will be especially noticeable in cold and / or rainy conditions.
5. be susceptible to aquaplaning when used with low tread depths (3 -1.5mm) on wet roads, especially in heavy rain conditions. Users need to exercise caution in these conditions with careful monitoring of vehicle speed to avoid aquaplaning.
Based on the recommendations, I would say at 36 psi, you are a little low.
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Joined: Jan 2000
Posts: 23,478
Likes: 2
From: Chicago
Re: Toyo Air Pressure Sweet Spot (descartesfool)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">When subjected to heat, compressed air will expand at a greater rate compared to nitrogen.</TD></TR></TABLE>
I don't understand this statement, which is presented with no explanation. All gasses are subject to the physics equation:
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.
Can you please reconcile this claim against elementary physics, which it appears to contradict?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">Based on the recommendations, I would say at 36 psi, you are a little low.</TD></TR></TABLE>
Why do you say that? This statement seems to contradict the recommendations you quoted, which put 36 psi right in the recommended range for a 2639-pound (1197-kg) ITR:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">Vehicle Weight Optimum Hot Inflation Pressures
.
.
.
Heavy 1000 - 1400kg 34 - 40 psi</TD></TR></TABLE>
Modified by nsxtasy at 8:11 PM 6/24/2006
I don't understand this statement, which is presented with no explanation. All gasses are subject to the physics equation:
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.
Can you please reconcile this claim against elementary physics, which it appears to contradict?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">Based on the recommendations, I would say at 36 psi, you are a little low.</TD></TR></TABLE>
Why do you say that? This statement seems to contradict the recommendations you quoted, which put 36 psi right in the recommended range for a 2639-pound (1197-kg) ITR:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by descartesfool »</TD></TR><TR><TD CLASS="quote">Vehicle Weight Optimum Hot Inflation Pressures
.
.
.
Heavy 1000 - 1400kg 34 - 40 psi</TD></TR></TABLE>
Modified by nsxtasy at 8:11 PM 6/24/2006
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From: west, mich, usa
Re: Toyo Air Pressure Sweet Spot (nsxtasy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">I don't understand this statement, which is presented with no explanation. All gasses are subject to the physics equation:
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.
Can you please reconcile this claim against elementary physics, which it appears to contradict?</TD></TR></TABLE>
its the moisture content with air. since there is some water present (likely as a liquid in the form of some minor condensation), when it gets hot and some becomes a vapor, we have effectively increased "n" and the pressure increases.
the molar heat capacity of nitrogen and oxygen is actually pretty close and is not really a factor.
http://www.engineeringtoolbox.....html vs. http://www.engineeringtoolbox.....html
note that the above tables are mass based heat capacities and you will have to correct for molecular weight.
enjoy!
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.
Can you please reconcile this claim against elementary physics, which it appears to contradict?</TD></TR></TABLE>
its the moisture content with air. since there is some water present (likely as a liquid in the form of some minor condensation), when it gets hot and some becomes a vapor, we have effectively increased "n" and the pressure increases.
the molar heat capacity of nitrogen and oxygen is actually pretty close and is not really a factor.
http://www.engineeringtoolbox.....html vs. http://www.engineeringtoolbox.....html
note that the above tables are mass based heat capacities and you will have to correct for molecular weight.
enjoy!
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From: Chicagoland, IL
Re: Toyo Air Pressure Sweet Spot (tom91ita)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tom91ita »</TD></TR><TR><TD CLASS="quote">its the moisture content with air. </TD></TR></TABLE>
If you start with air at 33% humidity (dry summer day) from 1 bar absolute to 3 bars absolute, it'll be ~100% humidity when it makes it into your tire. Worse yet, when you compress it it will be warmer, and be able to suck even more water vapor into your tire. When it cools there'll be some condensation.
The statement as-written was wrong, but if you keep the underlying humidity assumption it seems to have some truth behind it.
If you start with air at 33% humidity (dry summer day) from 1 bar absolute to 3 bars absolute, it'll be ~100% humidity when it makes it into your tire. Worse yet, when you compress it it will be warmer, and be able to suck even more water vapor into your tire. When it cools there'll be some condensation.
The statement as-written was wrong, but if you keep the underlying humidity assumption it seems to have some truth behind it.
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From: Baltimore, MD
Re: Toyo Air Pressure Sweet Spot (nsxtasy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">I don't understand this statement, which is presented with no explanation. All gasses are subject to the physics equation:
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.</TD></TR></TABLE>
that is an IDEAL gas law. regualr air does not act ideally because like it was said due to humidity and water vapor
PV = nRT
which says that the pressure times the volume is proportional to the temperature, and would not be different for one gas from another.</TD></TR></TABLE>
that is an IDEAL gas law. regualr air does not act ideally because like it was said due to humidity and water vapor
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From: Chicagoland, IL
Re: Toyo Air Pressure Sweet Spot (GSRCRXsi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSRCRXsi »</TD></TR><TR><TD CLASS="quote">
that is an IDEAL gas law. regualr air does not act ideally because like it was said due to humidity and water vapor</TD></TR></TABLE>
well.. water vapor (gas), oxygen, nitrogen, etc. will generally behave ideal. When you have any LIQUID water, the partial pressure of water will increase dramatically with temperature, and the net pressure will rise hand-in-hand.
In a worst-case scenario, let's say there's enough water built up over time that it doesn't all vaporize at 100C / 212F.
At x PSI cold (20 C / 68 F), 0.32 PSI (17 mm/hg) is contributed by water.
At x PSI hot, (100 C / 212 F), 14.7 PSI (760 mm/hg) is contributed by water.
So, if you're counting on a 30 PSI tire to go to 37 PSI from 20C to 100C, it would instead go to about 51 PSI if you have enough water. It becomes a pressure cooker, in essence, the water isn't boiling because it's under pressure, and it helped create a bunch of that pressure.
It's no coincidence that the partial pressure of water at 100C is one atmosphere.. the boiling occurs because the pressure of water vapor exceceds the atmospheric pressure (and the definition of 100C is the boiling point of water at 1 atmosphere, or at least it used to be a long time ago)
Sorry if this is rudimentary or pointing out the obvious, but I just wanted to make sure the mechanism for "water" to distort the temperature rise was clear.
-Chris
Table of vapor pressure of water vs. temperature: http://hyperphysics.phy-astr.g...ml#c1 (divide mm/hg by 51.7 to get PSI)
Edit:
For more fun, here's how much water you'd need to get this ~14 PSI tire pressure rise from 20C to 100C (212 F):
Volume of air in a 23" i.d. tire, 7" wide, 15" o.d. wheel: 1.5 liters
Moles of water in 1.5 liters at 100C and 1 atmosphere: 1.5L / 22.4 (avogadro's constant) * (273K/373K) = 0.05 moles
weight of 0.05 moles of H2O: (1+1+16) * 0.05 = 0.9 grams
This is about 0.9cc of water. That's .18 teaspoons. That's all it takes to throw off your tire pressure by 14 PSI at 100 C.
Modified by Chris F at 12:42 AM 6/25/2006
Modified by Chris F at 12:43 AM 6/25/2006
Modified by Chris F at 10:27 AM 6/25/2006
that is an IDEAL gas law. regualr air does not act ideally because like it was said due to humidity and water vapor</TD></TR></TABLE>
well.. water vapor (gas), oxygen, nitrogen, etc. will generally behave ideal. When you have any LIQUID water, the partial pressure of water will increase dramatically with temperature, and the net pressure will rise hand-in-hand.
In a worst-case scenario, let's say there's enough water built up over time that it doesn't all vaporize at 100C / 212F.
At x PSI cold (20 C / 68 F), 0.32 PSI (17 mm/hg) is contributed by water.
At x PSI hot, (100 C / 212 F), 14.7 PSI (760 mm/hg) is contributed by water.
So, if you're counting on a 30 PSI tire to go to 37 PSI from 20C to 100C, it would instead go to about 51 PSI if you have enough water. It becomes a pressure cooker, in essence, the water isn't boiling because it's under pressure, and it helped create a bunch of that pressure.
It's no coincidence that the partial pressure of water at 100C is one atmosphere.. the boiling occurs because the pressure of water vapor exceceds the atmospheric pressure (and the definition of 100C is the boiling point of water at 1 atmosphere, or at least it used to be a long time ago)
Sorry if this is rudimentary or pointing out the obvious, but I just wanted to make sure the mechanism for "water" to distort the temperature rise was clear.
-Chris
Table of vapor pressure of water vs. temperature: http://hyperphysics.phy-astr.g...ml#c1 (divide mm/hg by 51.7 to get PSI)
Edit:
For more fun, here's how much water you'd need to get this ~14 PSI tire pressure rise from 20C to 100C (212 F):
Volume of air in a 23" i.d. tire, 7" wide, 15" o.d. wheel: 1.5 liters
Moles of water in 1.5 liters at 100C and 1 atmosphere: 1.5L / 22.4 (avogadro's constant) * (273K/373K) = 0.05 moles
weight of 0.05 moles of H2O: (1+1+16) * 0.05 = 0.9 grams
This is about 0.9cc of water. That's .18 teaspoons. That's all it takes to throw off your tire pressure by 14 PSI at 100 C.
Modified by Chris F at 12:42 AM 6/25/2006
Modified by Chris F at 12:43 AM 6/25/2006
Modified by Chris F at 10:27 AM 6/25/2006
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From: Jasmaville, KS
Re: Toyo Air Pressure Sweet Spot (Chris F)
George - I have been running my full tread RA1's at 40f/42r HOT.
Over that, they get greasy, under that, I personally feel like they are a bit squshy.
I'll let the experts discuss entrophy & whatever other things I missed in science class
That's my .02.
Over that, they get greasy, under that, I personally feel like they are a bit squshy.
I'll let the experts discuss entrophy & whatever other things I missed in science class
That's my .02.
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From: Siege Perilous
Re: Toyo Air Pressure Sweet Spot (BudMan)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BudMan »</TD></TR><TR><TD CLASS="quote">I'll let the experts discuss entrophy & whatever other things I missed in science class </TD></TR></TABLE>
They definitely went over this old man's head.
</TD></TR></TABLE>They definitely went over this old man's head.
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From: Chicago
Re: Toyo Air Pressure Sweet Spot (George Knighton)
Just to sum up where we are...
1. Several of us have noted that we like cold pressures in the low thirties and hot pressures around 40 on our ITRs.
2. For an ITR or similar car, this is consistent with the recommendations on Toyo's website in the U.S., which recommends pressures of high thirties to low forties (for all cars), and their website in Australia, which recommends hot pressures of 34-40 for a car the size of the ITR. It is slightly lower than the Canadian recommendation of 41-43 (for all cars).
3. The Australian website also points out a possible explanation why pressures 5 psi higher than that, as reported by George about Mr. Roush's TL, are also consistent with Toyo's recommendations in Australia. The Australian website recommends higher pressures for a heavier car, with recommended hot pressures of 38-45 psi for a car weighing over 1400 kg, 4-5 psi higher than for cars weighing 1000-1400 kg. A new, stock TL has a curb weight of 3483 pounds, or 1580 kg, so the higher pressure would be appropriate, based on the website recommendation.
1. Several of us have noted that we like cold pressures in the low thirties and hot pressures around 40 on our ITRs.
2. For an ITR or similar car, this is consistent with the recommendations on Toyo's website in the U.S., which recommends pressures of high thirties to low forties (for all cars), and their website in Australia, which recommends hot pressures of 34-40 for a car the size of the ITR. It is slightly lower than the Canadian recommendation of 41-43 (for all cars).
3. The Australian website also points out a possible explanation why pressures 5 psi higher than that, as reported by George about Mr. Roush's TL, are also consistent with Toyo's recommendations in Australia. The Australian website recommends higher pressures for a heavier car, with recommended hot pressures of 38-45 psi for a car weighing over 1400 kg, 4-5 psi higher than for cars weighing 1000-1400 kg. A new, stock TL has a curb weight of 3483 pounds, or 1580 kg, so the higher pressure would be appropriate, based on the website recommendation.
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From: Chicagoland, IL
Re: Toyo Air Pressure Sweet Spot (BudMan)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BudMan »</TD></TR><TR><TD CLASS="quote">entrophy</TD></TR></TABLE>
Is that like an award for research in thermodynamics?
(more commonly spelled entropy)
Is that like an award for research in thermodynamics?
(more commonly spelled entropy)
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Joined: Jun 2004
Posts: 10,399
Likes: 3
From: Chicagoland, IL
Re: Toyo Air Pressure Sweet Spot (Chris F)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F »</TD></TR><TR><TD CLASS="quote">blah blah rambling partial pressure of water blah</TD></TR></TABLE>
Cliff notes: If you have a quarter tablespoon of actual liquid water in your tire, your tire pressure will be off by an additional 14 PSI when it reaches 212F. This is the reasoning behind nitrogen-filled tires, it should completely avoid this possibility of your tires *actually* achieving 50 PSI when you were shooting for 36 PSI.
A 30 PSI filled nitrogen tire at 68F will reach 36-37 PSI at 212F. add a quarter of a tablespoon of water and it will reach 50 PSI at the same temperature.
If you've ever filled a street tire at a gas station, I hope you release some air from the pump's nozzle first, because a bunch of water usually squirts out before the clean air does.
Cliff notes: If you have a quarter tablespoon of actual liquid water in your tire, your tire pressure will be off by an additional 14 PSI when it reaches 212F. This is the reasoning behind nitrogen-filled tires, it should completely avoid this possibility of your tires *actually* achieving 50 PSI when you were shooting for 36 PSI.
A 30 PSI filled nitrogen tire at 68F will reach 36-37 PSI at 212F. add a quarter of a tablespoon of water and it will reach 50 PSI at the same temperature.
If you've ever filled a street tire at a gas station, I hope you release some air from the pump's nozzle first, because a bunch of water usually squirts out before the clean air does.
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Re: Toyo Air Pressure Sweet Spot (George Knighton)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by George Knighton »</TD></TR><TR><TD CLASS="quote">
Am I right that pressures need to be a lot lower, or am I being an idiot again?</TD></TR></TABLE>
I skipped all the babbling above. so forgive me if this was already mentioned.
Wouldn't the sweet spot be at a specific temperature, and not necessarily a specific pressure?
most tires do have a specific operating temperature, im guessing taking tire temps is the way to figure out what pressures would be optimal.
Am I right that pressures need to be a lot lower, or am I being an idiot again?</TD></TR></TABLE>
I skipped all the babbling above. so forgive me if this was already mentioned.
Wouldn't the sweet spot be at a specific temperature, and not necessarily a specific pressure?
most tires do have a specific operating temperature, im guessing taking tire temps is the way to figure out what pressures would be optimal.
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Joined: Jun 2004
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From: Chicagoland, IL
Re: Toyo Air Pressure Sweet Spot (George Knighton)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by George Knighton »</TD></TR><TR><TD CLASS="quote">
Afro Takumi Says: "Stop confusing old humans!"</TD></TR></TABLE>
Bwhahaha!
Afro Takumi Says: "Stop confusing old humans!"</TD></TR></TABLE>
Bwhahaha!
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From: Cogito ergo sum, Canada
Re: Toyo Air Pressure Sweet Spot (Chris F)
I guess I should have read that nitrogen part of the Toyo Australia web site more carefully before I copied it to the post. It contains many false statements as do virtually all the claims made by various people/companies/organizations promoting the use of nitrogen in tires for non racing applications. Obviously nitrogen will obey the gas law as does air as does oxygen, and all these gases will go up and down in pressure an equal amount for and equal temperature rise in a closed volume like a tire. Here is a piece from Goodyear's web site on nitrogen inflation:
"Over the years, nitrogen inflation has been proposed for various types of tires, including large earth mover tires down through small passenger tires. At the present time, Goodyear endorses nitrogen inflation for certain sizes of earthmover tires used in particular applications, and has issued detailed instructions for these tires. Anyone concerned with applying or maintaining earthmover tires should be aware of the Goodyear Service Department Bulletins and Off-the-Road Tire Training Manuals that contain details of nitrogen inflation recommendations for these large off-the-road tires. The issue of nitrogen inflation for over-the-road truck tires is not quite so clear. Various performance improvements have been claimed, including better tread wear, casingd urability, and reduced susceptibility to tire fires. Although little actual controlled test data exists, a summary of Goodyear’s experience with nitrogen inflation for truck tires is the basis for the following comments. Tread wear appears to be affected negligibly by the tire inflation medium. Specifically, there is little, if any, treadlife change to be expected by using nitrogen inflation compared to normal air. So far as casing durability and retread-ability are concerned, the primary criteria is to avoid moisture in what-ever inflation medium is used. To this end, we strongly encourage proper selection of compressor equipment, air-line routing, the use of air dryers, and other good shop practices to avoid the introduction of moisture into high pressure air used for both initial tire inflation and make-up air. Again, we know of no significantly improved casing durability or retread durability performance to be expected from nitrogen inflation in over-the-road truck tires. Reduced rim or wheel corrosion has also been cited as an advantage of nitrogen inflation. However, corrosion is primarily the result of excessive moisture introduced by air that has not been properly dried, rather than a direct result of air versus nitrogen inflation. An additional concern is that past studies have shown that a very small percentage of non-nitrogen make-up inflation significantly contaminates the contained nitrogen atmosphere within a tire. In other words, if any benefits are to accrue from nitrogen inflation, it is essential that virtually all make-up inflation throughout the life of the tire/wheel assembly be diligently controlled to assure a near 100 percent nitrogen environment. A final issue is that of insuring against tire fires and/or self-ignition of tires resulting from excessive heat. For truck tires, this concern has been greatly reduced in recent years, primarily because of the changes from bias to radial tires and from tube-type to tubeless tires. The tubeless radial tire is simply much less susceptible to a tire fire than a bias tube-type design. This is partly because of the simplicity of the tubeless design (i.e. no separate tube and flap to create heat from rubbing or internal friction when the assembly deflates or runs severely underinflated or overloaded), and partly because steel radial truck tires require higher temperatures for a fire to start than their fabric-reinforced bias-ply counterparts. In summary, nitrogen inflation appears to have significant advantages for certain sizes and applications of large off-road tires, especially those operating in extremely high load or speed environments. However, nitrogen inflation appears to have quite small, perhaps insignificant, advantages for over-the-road truck tires."
I think that piece covers most of the claims made. Now as has been stated by others in this post, if you introduce liquid water droplets into a tire from the compressor, this liquid water can vaporise in the tire at high temperatures seen on track, and change the pressure significantly. It is this liquid water in the form of fine droplets that is the problem solved by using nitrogen for tire inflation. However as Goodyear states above, one should use proper air drying equipment to inflate tires, and then there are no benefits from nitrogen over dried air.
As far as tire pressure goes, my experience using pyrometers on my and my friend's cars on track using Toyo's for various weight cars (ITR's, BMW's, NSX, Porsches), the optimum tire temperature seems to match a hot pressure in the low 40's, as recommended on the Toyo Canada web site. Obviously the thing to check is temperatures and not pressures, but pressure is more convenient. I say buy a pyrometer and a digital tire pressure gauge and some log sheets to put your notes on. Once your car is really dialed in, then small changes to pressure around the optimum can be used to tune the balance of the car. Just don't use pressures to tune a non sorted car.
"Over the years, nitrogen inflation has been proposed for various types of tires, including large earth mover tires down through small passenger tires. At the present time, Goodyear endorses nitrogen inflation for certain sizes of earthmover tires used in particular applications, and has issued detailed instructions for these tires. Anyone concerned with applying or maintaining earthmover tires should be aware of the Goodyear Service Department Bulletins and Off-the-Road Tire Training Manuals that contain details of nitrogen inflation recommendations for these large off-the-road tires. The issue of nitrogen inflation for over-the-road truck tires is not quite so clear. Various performance improvements have been claimed, including better tread wear, casingd urability, and reduced susceptibility to tire fires. Although little actual controlled test data exists, a summary of Goodyear’s experience with nitrogen inflation for truck tires is the basis for the following comments. Tread wear appears to be affected negligibly by the tire inflation medium. Specifically, there is little, if any, treadlife change to be expected by using nitrogen inflation compared to normal air. So far as casing durability and retread-ability are concerned, the primary criteria is to avoid moisture in what-ever inflation medium is used. To this end, we strongly encourage proper selection of compressor equipment, air-line routing, the use of air dryers, and other good shop practices to avoid the introduction of moisture into high pressure air used for both initial tire inflation and make-up air. Again, we know of no significantly improved casing durability or retread durability performance to be expected from nitrogen inflation in over-the-road truck tires. Reduced rim or wheel corrosion has also been cited as an advantage of nitrogen inflation. However, corrosion is primarily the result of excessive moisture introduced by air that has not been properly dried, rather than a direct result of air versus nitrogen inflation. An additional concern is that past studies have shown that a very small percentage of non-nitrogen make-up inflation significantly contaminates the contained nitrogen atmosphere within a tire. In other words, if any benefits are to accrue from nitrogen inflation, it is essential that virtually all make-up inflation throughout the life of the tire/wheel assembly be diligently controlled to assure a near 100 percent nitrogen environment. A final issue is that of insuring against tire fires and/or self-ignition of tires resulting from excessive heat. For truck tires, this concern has been greatly reduced in recent years, primarily because of the changes from bias to radial tires and from tube-type to tubeless tires. The tubeless radial tire is simply much less susceptible to a tire fire than a bias tube-type design. This is partly because of the simplicity of the tubeless design (i.e. no separate tube and flap to create heat from rubbing or internal friction when the assembly deflates or runs severely underinflated or overloaded), and partly because steel radial truck tires require higher temperatures for a fire to start than their fabric-reinforced bias-ply counterparts. In summary, nitrogen inflation appears to have significant advantages for certain sizes and applications of large off-road tires, especially those operating in extremely high load or speed environments. However, nitrogen inflation appears to have quite small, perhaps insignificant, advantages for over-the-road truck tires."
I think that piece covers most of the claims made. Now as has been stated by others in this post, if you introduce liquid water droplets into a tire from the compressor, this liquid water can vaporise in the tire at high temperatures seen on track, and change the pressure significantly. It is this liquid water in the form of fine droplets that is the problem solved by using nitrogen for tire inflation. However as Goodyear states above, one should use proper air drying equipment to inflate tires, and then there are no benefits from nitrogen over dried air.
As far as tire pressure goes, my experience using pyrometers on my and my friend's cars on track using Toyo's for various weight cars (ITR's, BMW's, NSX, Porsches), the optimum tire temperature seems to match a hot pressure in the low 40's, as recommended on the Toyo Canada web site. Obviously the thing to check is temperatures and not pressures, but pressure is more convenient. I say buy a pyrometer and a digital tire pressure gauge and some log sheets to put your notes on. Once your car is really dialed in, then small changes to pressure around the optimum can be used to tune the balance of the car. Just don't use pressures to tune a non sorted car.
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From: Jasmaville, KS
Re: Toyo Air Pressure Sweet Spot (Chris F)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F »</TD></TR><TR><TD CLASS="quote">
Is that like an award for research in thermodynamics?
(more commonly spelled entropy)</TD></TR></TABLE>
The joke has carried on. If I would have speeeled it correctly, it would have appeared as though I may actually have a functioning brain cell that could comprehend such jibberish.
Is that like an award for research in thermodynamics?
(more commonly spelled entropy)</TD></TR></TABLE>
The joke has carried on. If I would have speeeled it correctly, it would have appeared as though I may actually have a functioning brain cell that could comprehend such jibberish.
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From: Chicago
Re: Toyo Air Pressure Sweet Spot (Driven)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Driven »</TD></TR><TR><TD CLASS="quote">here's what I've run my toyo ra1s at...cold pressure, i tend to forget to check pressures during the day:
24F
26R
1950lb CRX w/ driver. </TD></TR></TABLE>
That's consistent with the theory behind the Aussie advice, that lighter cars need less pressure than heavier ones (note that they weren't specific regarding whether "vehicle weight" included driver and/or fluids)...
24F
26R
1950lb CRX w/ driver. </TD></TR></TABLE>
That's consistent with the theory behind the Aussie advice, that lighter cars need less pressure than heavier ones (note that they weren't specific regarding whether "vehicle weight" included driver and/or fluids)...
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From: formerly elgorey, VIRginia
Re: Toyo Air Pressure Sweet Spot (nsxtasy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">(note that they weren't specific regarding whether "vehicle weight" included driver and/or fluids)...
</TD></TR></TABLE>
Unless you drive Herbie, whenever the car is on track using them tires, its got fluids and a driver!
</TD></TR></TABLE>
Unless you drive Herbie, whenever the car is on track using them tires, its got fluids and a driver!
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