Speedo / odometer accuracy for 92-00 Civic / 94-01 Integra owners...........
11-15-2007, 05:41 AM
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Speedo / odometer accuracy for 92-00 Civic / 94-01 Integra owners...........
Regarding speedo and odometer accuracy……………………
I don’t know if this has ever been covered in previous posts. If you already are aware, or don’t give a ****, then disregard. But for those who are unaware, do care, or are new to Hondas and Acuras, then please read on.
When our Civics and Integras were stock, they came with 14 or 15 inch wheels with multiple tire sizes depending on model. I am here to tell you that the speedo and odometer MAY NOT BE ACCURATE with the stock tire sizes…………………between 3-11% depending on the stock tire size that came on the car. The only way to verify is by taking the car to a speedo calibration shop.
As many know, the whole system runs off the electronic vehicle speed sensor in the tranny and is driven by the supplemental ring gear on the edge of the differential and the gear attached to the speed sensor itself. Unless I am mistaken (95% sure that I am not), both those gears have the exact same ratio regardless of which Civic or Integra B or D series manual tranny you have. I cannot vouch for speedo gears in the automatic trannies. With the stock tire sizes, the only real variable is how the speed sensor electronic voltage signal itself is performing. Swapping speed sensors may or may not solve the problem. Chances are though that the vehicle speed sensor is functioning AS DESIGNED.
I bought my 1995 Civic EX coupe new and immediately noticed this flaw. When my gauges were reading 70mph, I was really doing 64mph. That 9% difference was also consistent at other speeds as well. The odometer was registering 1.1 miles per every mile driven. I had this verified by a speedo calibration shop. I had the stock 185/60/14 tire size. I took the car to the dealer and they replaced the speedo cluster, which didn’t solve anything. When I later went to 195/50/15 tires, the accuracy stayed the same. I drove the car like that for a few years and mentally compensated. My mileage accumulated a few extra thousand miles more than it should have.
In 2001, I switched to my current tire size of 205/40/17. With my original D series manual tranny, my speedo accuracy increased to 99-100% depending on my speed. My odometer has been perfect ever since.
In 2006, I swapped in a B series with an ITR tranny with factory LSD. I had the speedo and odometer checked again and it was exactly the same as my D series tranny.
So in summary, assuming that all B and D series manual tranny vehicle speed sensors are operating as designed, the only true fix is to use a tire size that has a total properly inflated external diameter of 23.5 inches to achieve 99-100% accuracy. Here is a rundown of some of the popular 92-00 Civic and 94-01 Integra tire sizes and their external diameters. These numbers were derived from Toyos website. There may be very small deviations in tire size dimensions from one tire manufacturer to the next. Smaller overall diameters mean more revolutions from point A to B, and vice versa for larger overall diameters. If all you do is race, then smaller is the way to go for most. But of you want accuracy for your street car, then follow this chart next time you decide to go with a new wheel and tire size:
Tire size.............Overall diameter......Reading / Actual................Accuracy rate
205/40/16..........22.5 inches...............70mph / 60.9mph.............87% accuracy
175/70/13..........22.7 inches...............70mph / 62.3mph.............89% accuracy
185/60/14..........22.8 inches...............70mph / 63.7mph.............91% accuracy
195/50/15..........22.8 inches...............70mph / 63.7mph.............91% accuracy
205/50/15..........23.1 inches...............70mph / 65.8mph.............94% accuracy
205/45/16..........23.3 inches...............70mph / 66.9mph.............95.5% accuracy
195/55/15..........23.4 inches...............70mph / 67.9mph.............97% accuracy
205/40/17..........23.5 inches...............70mph / 69.3mph.............99% accuracy
225/50/15..........23.9 inches...............70mph / 74.2mph.............94% accuracy
Modified by Toy Civic at 8:55 PM 11/30/2007
Modified by Toy Civic at 8:56 PM 11/30/2007
I don’t know if this has ever been covered in previous posts. If you already are aware, or don’t give a ****, then disregard. But for those who are unaware, do care, or are new to Hondas and Acuras, then please read on.
When our Civics and Integras were stock, they came with 14 or 15 inch wheels with multiple tire sizes depending on model. I am here to tell you that the speedo and odometer MAY NOT BE ACCURATE with the stock tire sizes…………………between 3-11% depending on the stock tire size that came on the car. The only way to verify is by taking the car to a speedo calibration shop.
As many know, the whole system runs off the electronic vehicle speed sensor in the tranny and is driven by the supplemental ring gear on the edge of the differential and the gear attached to the speed sensor itself. Unless I am mistaken (95% sure that I am not), both those gears have the exact same ratio regardless of which Civic or Integra B or D series manual tranny you have. I cannot vouch for speedo gears in the automatic trannies. With the stock tire sizes, the only real variable is how the speed sensor electronic voltage signal itself is performing. Swapping speed sensors may or may not solve the problem. Chances are though that the vehicle speed sensor is functioning AS DESIGNED.
I bought my 1995 Civic EX coupe new and immediately noticed this flaw. When my gauges were reading 70mph, I was really doing 64mph. That 9% difference was also consistent at other speeds as well. The odometer was registering 1.1 miles per every mile driven. I had this verified by a speedo calibration shop. I had the stock 185/60/14 tire size. I took the car to the dealer and they replaced the speedo cluster, which didn’t solve anything. When I later went to 195/50/15 tires, the accuracy stayed the same. I drove the car like that for a few years and mentally compensated. My mileage accumulated a few extra thousand miles more than it should have.
In 2001, I switched to my current tire size of 205/40/17. With my original D series manual tranny, my speedo accuracy increased to 99-100% depending on my speed. My odometer has been perfect ever since.
In 2006, I swapped in a B series with an ITR tranny with factory LSD. I had the speedo and odometer checked again and it was exactly the same as my D series tranny.
So in summary, assuming that all B and D series manual tranny vehicle speed sensors are operating as designed, the only true fix is to use a tire size that has a total properly inflated external diameter of 23.5 inches to achieve 99-100% accuracy. Here is a rundown of some of the popular 92-00 Civic and 94-01 Integra tire sizes and their external diameters. These numbers were derived from Toyos website. There may be very small deviations in tire size dimensions from one tire manufacturer to the next. Smaller overall diameters mean more revolutions from point A to B, and vice versa for larger overall diameters. If all you do is race, then smaller is the way to go for most. But of you want accuracy for your street car, then follow this chart next time you decide to go with a new wheel and tire size:
Tire size.............Overall diameter......Reading / Actual................Accuracy rate
205/40/16..........22.5 inches...............70mph / 60.9mph.............87% accuracy
175/70/13..........22.7 inches...............70mph / 62.3mph.............89% accuracy
185/60/14..........22.8 inches...............70mph / 63.7mph.............91% accuracy
195/50/15..........22.8 inches...............70mph / 63.7mph.............91% accuracy
205/50/15..........23.1 inches...............70mph / 65.8mph.............94% accuracy
205/45/16..........23.3 inches...............70mph / 66.9mph.............95.5% accuracy
195/55/15..........23.4 inches...............70mph / 67.9mph.............97% accuracy
205/40/17..........23.5 inches...............70mph / 69.3mph.............99% accuracy
225/50/15..........23.9 inches...............70mph / 74.2mph.............94% accuracy
Modified by Toy Civic at 8:55 PM 11/30/2007
Modified by Toy Civic at 8:56 PM 11/30/2007
11-15-2007, 07:27 AM
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Re: (siksdb8)
so my 97 civic, with 205/50/15 tires, assuming that my VSS is working properly.... based on our chart, when i am traveling at 70mph, i am really going 65.8, then? when i drive by those portable speed things the police put out, i notice it is only off by like 3mph... but aren't those off too?
11-15-2007, 07:32 AM
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Re: (ITLNstallion818)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITLNstallion818 »</TD></TR><TR><TD CLASS="quote">so my 97 civic, with 205/50/15 tires, assuming that my VSS is working properly.... based on our chart, when i am traveling at 70mph, i am really going 65.8, then? when i drive by those portable speed things the police put out, i notice it is only off by like 3mph... but aren't those off too?</TD></TR></TABLE>
Yes they are. I always see them off by 1-2 mph.
Yes they are. I always see them off by 1-2 mph.
11-15-2007, 07:53 AM
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Re: (ITLNstallion818)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITLNstallion818 »</TD></TR><TR><TD CLASS="quote">how accurate is the fact that 70mph= 65.8mph with 205/50/15 tires? not saying this is a joke, im just curious</TD></TR></TABLE>
I'd say about 95% accurate.
Here is what I know for sure. And assuming that all VSS units are functioning the same.
With 185/60/14 and 195/50/15 tires having a 22.8 inch diameter, I WAS only 91% accurate. I have the calibration sheet to prove it.
My 205/40/17 tires with a 23.5 inch diameter had 99% accuracy. Again, I have the calibration sheet to prove it.
The difference between 23.5 and 22.8 inches is 0.7 inches and 8%. Do the math and you get a 1% decrease in accuracy every 0.0875 inches as the tire size decreases from the magic number of 23.5 inches.
I'd say about 95% accurate.
Here is what I know for sure. And assuming that all VSS units are functioning the same.
With 185/60/14 and 195/50/15 tires having a 22.8 inch diameter, I WAS only 91% accurate. I have the calibration sheet to prove it.
My 205/40/17 tires with a 23.5 inch diameter had 99% accuracy. Again, I have the calibration sheet to prove it.
The difference between 23.5 and 22.8 inches is 0.7 inches and 8%. Do the math and you get a 1% decrease in accuracy every 0.0875 inches as the tire size decreases from the magic number of 23.5 inches.
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11-15-2007, 10:24 AM
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Re: (ITLNstallion818)
First of all, all speed sensor units do NOT function the same. So just because the speedometer on your '95 Civic is off by 9 percent with the stock size tires, does not mean that anyone else's speedometer is going to be off by 9 percent, even if it's the same year and model car.
As for tire sizes, it's easy to calculate differences in the sizes that are labeled on the side of the tire. For example, if your stock tire size is 185/60-14, and your speedometer reads 9 percent higher than your actual speed, if you switch to 205/40-17, that size is 3.2 percent larger. So all things being equal, your speedometer will then read 5.8 percent high instead of 9 percent.
But there are lots more causes of speedometer error. Some tires are larger than others, even when they are marked with the same size on the sidewall. Tire manufacturers have some latitude in marking their sizes, so they can only be considered approximate. This alone can account for differences of 3-5 percent. Even treadwear can result in speedometer error; for example, the difference in diameter between a tire that is brand new and one that has worn down to the treadwear indicator bars (2/32" tread depth) is about 2 percent, and that goes into speedometer error as well.
The bottom line is this: Anyone who is interested in verifying the accuracy of his speedometer can, and should, do so (such as by using a GPS to measure speed), but even then, it is only an approximation that can change over time.
We have a '94 Integra GS-R, an '01 Integra Type R, and a '91 NSX. With tires labeled as the stock size, the speedometers on all three are accurate to within 1-2 percent.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITLNstallion818 »</TD></TR><TR><TD CLASS="quote">so my 97 civic, with 205/50/15 tires, assuming that my VSS is working properly.... based on our chart, when i am traveling at 70mph, i am really going 65.8, then?</TD></TR></TABLE>
No. He has found those numbers to be accurate for his car. Your car can be, and probably is, totally different.
Your car came with 185/65-14 tires from the factory. 205/50-15 is 1.7 percent smaller in calculated diameter. So therefore, if your speedometer is accurate when it has the stock tires on it, then when it says you are going 70 mph, you're really going 68.8 mph with 205/50-15 tires. If it was not accurate with the stock size tires, then whatever it said then, changing to 205/50-15 makes it read 1.7 percent higher. This is aside from all those other factors that affect speedometer accuracy, such as tire tread depth, differences in actual tire sizes for specific makes/models/sizes of tire, and any inaccuracy inherent in your car's VSS/speedometer system.
As for tire sizes, it's easy to calculate differences in the sizes that are labeled on the side of the tire. For example, if your stock tire size is 185/60-14, and your speedometer reads 9 percent higher than your actual speed, if you switch to 205/40-17, that size is 3.2 percent larger. So all things being equal, your speedometer will then read 5.8 percent high instead of 9 percent.
But there are lots more causes of speedometer error. Some tires are larger than others, even when they are marked with the same size on the sidewall. Tire manufacturers have some latitude in marking their sizes, so they can only be considered approximate. This alone can account for differences of 3-5 percent. Even treadwear can result in speedometer error; for example, the difference in diameter between a tire that is brand new and one that has worn down to the treadwear indicator bars (2/32" tread depth) is about 2 percent, and that goes into speedometer error as well.
The bottom line is this: Anyone who is interested in verifying the accuracy of his speedometer can, and should, do so (such as by using a GPS to measure speed), but even then, it is only an approximation that can change over time.
We have a '94 Integra GS-R, an '01 Integra Type R, and a '91 NSX. With tires labeled as the stock size, the speedometers on all three are accurate to within 1-2 percent.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITLNstallion818 »</TD></TR><TR><TD CLASS="quote">so my 97 civic, with 205/50/15 tires, assuming that my VSS is working properly.... based on our chart, when i am traveling at 70mph, i am really going 65.8, then?</TD></TR></TABLE>
No. He has found those numbers to be accurate for his car. Your car can be, and probably is, totally different.
Your car came with 185/65-14 tires from the factory. 205/50-15 is 1.7 percent smaller in calculated diameter. So therefore, if your speedometer is accurate when it has the stock tires on it, then when it says you are going 70 mph, you're really going 68.8 mph with 205/50-15 tires. If it was not accurate with the stock size tires, then whatever it said then, changing to 205/50-15 makes it read 1.7 percent higher. This is aside from all those other factors that affect speedometer accuracy, such as tire tread depth, differences in actual tire sizes for specific makes/models/sizes of tire, and any inaccuracy inherent in your car's VSS/speedometer system.
11-15-2007, 09:09 PM
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Re: (nsxtasy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">First of all, all speed sensor units do NOT function the same. So just because the speedometer on your '95 Civic is off by 9 percent with the stock size tires, does not mean that anyone else's speedometer is going to be off by 9 percent, even if it's the same year and model car.
As for tire sizes, it's easy to calculate differences in the sizes that are labeled on the side of the tire. For example, if your stock tire size is 185/60-14, and your speedometer reads 9 percent higher than your actual speed, if you switch to 205/40-17, that size is 3.2 percent larger. So all things being equal, your speedometer will then read 5.8 percent high instead of 9 percent.
We have a '94 Integra GS-R, an '01 Integra Type R, and a '91 NSX. With tires labeled as the stock size, the speedometers on all three are accurate to within 1-2 percent.
No. He has found those numbers to be accurate for his car. Your car can be, and probably is, totally different
</TD></TR></TABLE>
If I am not mistaken, the stock tire size of the Integra GSR's and Integra Type R's were 195/55/15. Based on the chart I provided of that tire size, they come closest to the magic number of a 23.5 inch diameter.
But in todays world, especially with the whole JDM craze, less are sticking to the original tire size, even though they stay with 15 inch rims. Many are going with the alternate 15 inch tire sizes which will definitely affect speedo accuracy.
Yes I know that tire pressure and treadwear will also affect accuracy by as much as 1-2%.
My statement was, assuming all VSS units are working the same. I'll bet $10.00 that the majority of them are working in an equal manner in 92-00 Civics and 94-01 Integras. How else do you explain the identical readings I had between a D and B series tranny with different VSS units using the exact same tires.
As far as the percentages you quoted, I do not know how you came to those conclusions. But all I am saying is that I know what my values were accurate with 185/60/14 and then with 205/40/17. I've never used GPS, but I'm sure they will work great. But I can also say with certainty that a speedo calibration shop with dyno rollers is a sure fire way to verify the accuracy. Those shops are also the legal way to verify should someone have to go to court.
My point is that this is something that should be considered by 92-00 Civic and 94-01 Integra owners. Like I said, I cannot personally vouch for cars with auto trannies or any other Hondas. I do know that there was a recall of some late model Accords for this very same thing. I've also heard time and time again from H-T, other forums, as well as the speedo calibration shops that Hondas are notorious for having inaccurate speedo and odometer registration.
As for tire sizes, it's easy to calculate differences in the sizes that are labeled on the side of the tire. For example, if your stock tire size is 185/60-14, and your speedometer reads 9 percent higher than your actual speed, if you switch to 205/40-17, that size is 3.2 percent larger. So all things being equal, your speedometer will then read 5.8 percent high instead of 9 percent.
We have a '94 Integra GS-R, an '01 Integra Type R, and a '91 NSX. With tires labeled as the stock size, the speedometers on all three are accurate to within 1-2 percent.
No. He has found those numbers to be accurate for his car. Your car can be, and probably is, totally different
</TD></TR></TABLE>
If I am not mistaken, the stock tire size of the Integra GSR's and Integra Type R's were 195/55/15. Based on the chart I provided of that tire size, they come closest to the magic number of a 23.5 inch diameter.
But in todays world, especially with the whole JDM craze, less are sticking to the original tire size, even though they stay with 15 inch rims. Many are going with the alternate 15 inch tire sizes which will definitely affect speedo accuracy.
Yes I know that tire pressure and treadwear will also affect accuracy by as much as 1-2%.
My statement was, assuming all VSS units are working the same. I'll bet $10.00 that the majority of them are working in an equal manner in 92-00 Civics and 94-01 Integras. How else do you explain the identical readings I had between a D and B series tranny with different VSS units using the exact same tires.
As far as the percentages you quoted, I do not know how you came to those conclusions. But all I am saying is that I know what my values were accurate with 185/60/14 and then with 205/40/17. I've never used GPS, but I'm sure they will work great. But I can also say with certainty that a speedo calibration shop with dyno rollers is a sure fire way to verify the accuracy. Those shops are also the legal way to verify should someone have to go to court.
My point is that this is something that should be considered by 92-00 Civic and 94-01 Integra owners. Like I said, I cannot personally vouch for cars with auto trannies or any other Hondas. I do know that there was a recall of some late model Accords for this very same thing. I've also heard time and time again from H-T, other forums, as well as the speedo calibration shops that Hondas are notorious for having inaccurate speedo and odometer registration.
11-16-2007, 09:51 AM
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Re: (Toy Civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">If I am not mistaken, the stock tire size of the Integra GSR's and Integra Type R's were 195/55/15.</TD></TR></TABLE>
That's correct.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">My statement was, assuming all VSS units are working the same</TD></TR></TABLE>
They don't all work the same.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">How else do you explain the identical readings I had between a D and B series tranny with different VSS units using the exact same tires.</TD></TR></TABLE>
How else do you explain that the speedometer on my Integras are more accurate than on your Civic?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">As far as the percentages you quoted, I do not know how you came to those conclusions.</TD></TR></TABLE>
They're based on mathematical calculations using the tire sizes. You know (or apparently you don't know) - the diameter of the tire equals the diameter of the wheel plus twice the sidewall height, and the sidewall height is the aspect ratio times the treadwidth. There are calculators you can find on the internet that do all the computations for you.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">But all I am saying is that I know what my values were accurate with 185/60/14 and then with 205/40/17.</TD></TR></TABLE>
And for the particular tires you were using in each size, and the tread depth you had on those particular tires at the time.
Checking the accuracy of your speedometer from time to time, using GPS (best done at a constant speed over a period of time) or a calibration shop, is a good idea. Especially when you switch tire sizes or models, if you're really curious or if you have reason to believe the speed is off.
That's correct.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">My statement was, assuming all VSS units are working the same</TD></TR></TABLE>
They don't all work the same.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">How else do you explain the identical readings I had between a D and B series tranny with different VSS units using the exact same tires.</TD></TR></TABLE>
How else do you explain that the speedometer on my Integras are more accurate than on your Civic?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">As far as the percentages you quoted, I do not know how you came to those conclusions.</TD></TR></TABLE>
They're based on mathematical calculations using the tire sizes. You know (or apparently you don't know) - the diameter of the tire equals the diameter of the wheel plus twice the sidewall height, and the sidewall height is the aspect ratio times the treadwidth. There are calculators you can find on the internet that do all the computations for you.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">But all I am saying is that I know what my values were accurate with 185/60/14 and then with 205/40/17.</TD></TR></TABLE>
And for the particular tires you were using in each size, and the tread depth you had on those particular tires at the time.
Checking the accuracy of your speedometer from time to time, using GPS (best done at a constant speed over a period of time) or a calibration shop, is a good idea. Especially when you switch tire sizes or models, if you're really curious or if you have reason to believe the speed is off.
11-16-2007, 08:22 PM
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Re: (nsxtasy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">
How else do you explain that the speedometer on my Integras are more accurate than on your Civic? </TD></TR></TABLE>
Because again, you had the 195/55/15 tires. And those come very close to the 23.5 inch magic number in overall tire diameter. My Civic's original 185/60/14's were almost 3/4 inch smaller in overall diameter with the same VSS designs.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">
They don't all work the same.</TD></TR></TABLE>
Do you know this for sure??? I am specifically talking about the VSS units for 92-00 Civic and 94-01 Integras. I can understand your point if comparing Civics/Integras to say Accords or Preludes VSS units. But since Civics and Integras share about 60-70% of the same DNA, and knowing how the automotive industry works to standardize as much as possible, I'll bet that the VSS are all the same in manual tranny Civics and Integras. The big question is, are there variations in voltages sent to the speedo cluster??? Only a Honda trained or knowledgable tech can truly answer this question.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">
They're based on mathematical calculations using the tire sizes. You know (or apparently you don't know) - the diameter of the tire equals the diameter of the wheel plus twice the sidewall height, and the sidewall height is the aspect ratio times the treadwidth. There are calculators you can find on the internet that do all the computations for you.</TD></TR></TABLE>
That all sounds very valid. I'm definitely not a tire engineer. What I have always known though is the basics about tire size. For reference sake, 1 inch = 25.4mm. If you take your stock 195/55/15 tires on your Integras for example:
- 195 = the tread width in mm (7.67 inches)
- 15 = The wheel size.
- 55 = the aspect ratio tire sidewall height in relation to the tread width. It is measured from the bead to the tread. This number is expressed in percentage i.e. 55% of the 195mm treadwidth. So if you measured the sidewall height of the 195/55/15, the actual number would be 107.25mm (4.22 inches). Say if you changed to the ever popular 205/50/15 tire size, now you have a 205mm treadwidth (8.07 inches), and a 50 series sidewall height 102.5mm inches (4.03 inches).
So a 205/50/15 sounds like a bigger tire, but in reality, the diameter is smaller. The only advantage is about 1/2 inch wider tread, and a stiffer sidewall for cornering.
Speaking from the mathematical point of view, a smaller circle will roll 360 degrees in more revolutions from point A to point B than a larger circle. Tire calculators are not necessary to understand this. For speedo accuracy, the most important number is the overall tire diameter.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">Checking the accuracy of your speedometer from time to time, using GPS (best done at a constant speed over a period of time) or a calibration shop, is a good idea. Especially when you switch tire sizes or models, if you're really curious or if you have reason to believe the speed is off.
</TD></TR></TABLE>
I AGREE 100%. My whole point here is when you have a stock vehicle, Honda/Acura, or any other manufacturer for that matter. Before changing tire sizes, check the accuracy of the stock ones.
How else do you explain that the speedometer on my Integras are more accurate than on your Civic? </TD></TR></TABLE>
Because again, you had the 195/55/15 tires. And those come very close to the 23.5 inch magic number in overall tire diameter. My Civic's original 185/60/14's were almost 3/4 inch smaller in overall diameter with the same VSS designs.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">
They don't all work the same.</TD></TR></TABLE>
Do you know this for sure??? I am specifically talking about the VSS units for 92-00 Civic and 94-01 Integras. I can understand your point if comparing Civics/Integras to say Accords or Preludes VSS units. But since Civics and Integras share about 60-70% of the same DNA, and knowing how the automotive industry works to standardize as much as possible, I'll bet that the VSS are all the same in manual tranny Civics and Integras. The big question is, are there variations in voltages sent to the speedo cluster??? Only a Honda trained or knowledgable tech can truly answer this question.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">
They're based on mathematical calculations using the tire sizes. You know (or apparently you don't know) - the diameter of the tire equals the diameter of the wheel plus twice the sidewall height, and the sidewall height is the aspect ratio times the treadwidth. There are calculators you can find on the internet that do all the computations for you.</TD></TR></TABLE>
That all sounds very valid. I'm definitely not a tire engineer. What I have always known though is the basics about tire size. For reference sake, 1 inch = 25.4mm. If you take your stock 195/55/15 tires on your Integras for example:
- 195 = the tread width in mm (7.67 inches)
- 15 = The wheel size.
- 55 = the aspect ratio tire sidewall height in relation to the tread width. It is measured from the bead to the tread. This number is expressed in percentage i.e. 55% of the 195mm treadwidth. So if you measured the sidewall height of the 195/55/15, the actual number would be 107.25mm (4.22 inches). Say if you changed to the ever popular 205/50/15 tire size, now you have a 205mm treadwidth (8.07 inches), and a 50 series sidewall height 102.5mm inches (4.03 inches).
So a 205/50/15 sounds like a bigger tire, but in reality, the diameter is smaller. The only advantage is about 1/2 inch wider tread, and a stiffer sidewall for cornering.
Speaking from the mathematical point of view, a smaller circle will roll 360 degrees in more revolutions from point A to point B than a larger circle. Tire calculators are not necessary to understand this. For speedo accuracy, the most important number is the overall tire diameter.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy »</TD></TR><TR><TD CLASS="quote">Checking the accuracy of your speedometer from time to time, using GPS (best done at a constant speed over a period of time) or a calibration shop, is a good idea. Especially when you switch tire sizes or models, if you're really curious or if you have reason to believe the speed is off.
</TD></TR></TABLE>
I AGREE 100%. My whole point here is when you have a stock vehicle, Honda/Acura, or any other manufacturer for that matter. Before changing tire sizes, check the accuracy of the stock ones.
11-17-2007, 08:35 AM
#12
H-T Order of Merit
Re: (Toy Civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">Because again, you had the 195/55/15 tires. And those come very close to the 23.5 inch magic number in overall tire diameter. My Civic's original 185/60/14's were almost 3/4 inch smaller in overall diameter with the same VSS designs.</TD></TR></TABLE>
The difference in calculated outer diameter between 195/55-15 and 185/60-14 is about 3 percent. It does not explain your speedometer error of 9 percent.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">Do you know this for sure???</TD></TR></TABLE>
The fact that yours is off by 9 percent, and most folks don't have this problem, proves it.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">So a 205/50/15 sounds like a bigger tire, but in reality, the diameter is smaller. The only advantage is about 1/2 inch wider tread, and a stiffer sidewall for cornering.</TD></TR></TABLE>
And a disadvantage to the wider tires is poorer traction in rain. (However, these differences between 195/55 and 205/50 are all very very tiny, to the point of insignificance as a decision factor.)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">I AGREE 100%. My whole point here is when you have a stock vehicle, Honda/Acura, or any other manufacturer for that matter. Before changing tire sizes, check the accuracy of the stock ones.</TD></TR></TABLE>
The accuracy of the speedometer/odometer is not the only important consideration in choosing a tire size. Others include fit in the wheel wells without rubbing, acceleration (larger tires hurt acceleration), etc. If your speedometer is off by 9 percent with the stock size tires, your car has a problem; my recommendation is that you fix the problem, rather than adding another problem (wrong-sized tires) to try to offset its effects.
The difference in calculated outer diameter between 195/55-15 and 185/60-14 is about 3 percent. It does not explain your speedometer error of 9 percent.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">Do you know this for sure???</TD></TR></TABLE>
The fact that yours is off by 9 percent, and most folks don't have this problem, proves it.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">So a 205/50/15 sounds like a bigger tire, but in reality, the diameter is smaller. The only advantage is about 1/2 inch wider tread, and a stiffer sidewall for cornering.</TD></TR></TABLE>
And a disadvantage to the wider tires is poorer traction in rain. (However, these differences between 195/55 and 205/50 are all very very tiny, to the point of insignificance as a decision factor.)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">I AGREE 100%. My whole point here is when you have a stock vehicle, Honda/Acura, or any other manufacturer for that matter. Before changing tire sizes, check the accuracy of the stock ones.</TD></TR></TABLE>
The accuracy of the speedometer/odometer is not the only important consideration in choosing a tire size. Others include fit in the wheel wells without rubbing, acceleration (larger tires hurt acceleration), etc. If your speedometer is off by 9 percent with the stock size tires, your car has a problem; my recommendation is that you fix the problem, rather than adding another problem (wrong-sized tires) to try to offset its effects.
03-20-2008, 02:41 PM
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Re: Speedo / odometer accuracy for 92-00 Civic / 94-01 Integra owners........... (Toy Civic)
Yeah I just did a speed-match on my way home this morning with a new Si. They have those digital gauges and I could see how fast we were going a mile away. I was doing 71 mph according to my cluster in my 98 EX and according to his digital one we were doing 65-66! I was starting to wonder why I always had to haul *** or get ran over whenever I was driving my civic. Now I know my car is slow...it just thinks its faster than it really is! LOL!!!
05-09-2008, 08:13 AM
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The VSS of the same type should theoretically work exactly the same between vehicles. Why? It gives off a fixed number of pulses for every rotation of the gear it reads off of. This is assuming the gear size has the same # of teeth and so on.
The speedometer on the other hand is an analog output and may not be accurate.
The speedometer on the other hand is an analog output and may not be accurate.
05-14-2008, 08:27 AM
#17
Honda-Tech Member
Re: (erikiksaz1)
Found this thread. We have a Fit that reads high and I'm looking to see what I can find.
"If you bought or leased a model year 2002 through 2006 Honda or Acura automobile or a model year 2007 Honda Fit, in the United States or its territories, between April 13, 2002 and November 7, 2006, you may be entitled to receive benefits under a class action settlement. Details at http://www.hondaodometerclassaction.com/.
"If you bought or leased a model year 2002 through 2006 Honda or Acura automobile or a model year 2007 Honda Fit, in the United States or its territories, between April 13, 2002 and November 7, 2006, you may be entitled to receive benefits under a class action settlement. Details at http://www.hondaodometerclassaction.com/.
07-21-2008, 07:47 AM
#19
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Re: (erikiksaz1)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erikiksaz1 »</TD></TR><TR><TD CLASS="quote">When I first bought my GPS unit, I found out that I was actually going at about ~76-77 mph when my speedometer read 80mph. This was on 205/45/16 on an Integra.
</TD></TR></TABLE>
Same here while using that size of tire as well.
Interesting post Toy Civic.
</TD></TR></TABLE>
Same here while using that size of tire as well.
Interesting post Toy Civic.
07-21-2008, 09:29 AM
#20
H-T Order of Merit
Re: (Toy Civic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Toy Civic »</TD></TR><TR><TD CLASS="quote">bump</TD></TR></TABLE>
Stickied at the top of this forum is a topic:
Forum Rules and FAQ - READ BEFORE POSTING
It says:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Forum Rules and FAQ - READ BEFORE POSTING »</TD></TR><TR><TD CLASS="quote">
<FONT SIZE="4">Rules</FONT>
7. Bump once and if you still don't get the info you're looking for just let it die, don't bump it again. If you bump the topic a second time, the topic will be locked and you will lose points.</TD></TR></TABLE>
Stickied at the top of this forum is a topic:
Forum Rules and FAQ - READ BEFORE POSTING
It says:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Forum Rules and FAQ - READ BEFORE POSTING »</TD></TR><TR><TD CLASS="quote">
<FONT SIZE="4">Rules</FONT>
7. Bump once and if you still don't get the info you're looking for just let it die, don't bump it again. If you bump the topic a second time, the topic will be locked and you will lose points.</TD></TR></TABLE>
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