To what extent does the wear on a tire effect its operating temps? If I find the ideal camber (by equalizing cross tread temps) using a tire that has been unevenly worn (more wear on outside), how close will the tire temps for a fresh set of tires be, @ that same camber?

I'm trying to determine the degree of influence of both the altered tire geometry, and the differences in thermal mass so I can account for it when I set my camber.

Any other tips for camber tuning are welcome as I'm about to put the kits on the car. Skunk2 A arms, 205/50-15 RA1s. And, if your feeling generous, some opinions on swapping a arms, the resultant change in caster, and the shift/alteration of the caster/camber curve vs. ride height.

 

More tread on a section of tire will result in more squirm from the rubber. More squirm = higher temps. A tire with little to no tread will run cooler. A tire with less rubber on it will also run cooler, all things being equal.

 

your caster/camber curve should remain unchanged.

imo, using tire temperatures alone to dial in camber is merely a more educated guess then using tire wear. a better approach would be to use a g-meter combined with tire temperatures as you could conceivably have a situation where an ideal temperature spread might not generate as much grip as a less optimal temperature spread.

i know in my car the inner edge of my tires is significantly hotter then the rest of the tire. taking just that information, one would say i'm running too much negative camber. however, further analysis reveals that i'm still running insufficient amounts of camber for my tires and that the strange tire temp spread is due to the inside tire spinning at corner exit.

nate

 

So perhaps the error inherent in using solely tire temps negates the other factors I was talking about? I wouldn't doubt it. Unfortunately, a pyrometer is all I have to work with right now.

At any rate, still interested in the original question...


Modified by sackdz at 1:40 PM 9/29/2003

 

Anyone care to comment on my first question?

 

>>To what extent does the wear on a tire effect its operating temps?

Just a stab in the dark with the wand of Physics: heat is caused by friction, friction cause tire wear. so there is an indirect relationship through friction, but to say wear directly causes heat seems to be false, and instinctively backwards.

why do you ask? trying to affect tire temps? what are your readings?

 

Gah... I was just trying to title a thread so as not to confuse the hell out of anyone.

I have not taken temps yet, in fact the camber kits aren't even installed yet.

Basically I'm just asking a theoretical racing physics question.... I guess I'm not being understood so I'll try and clear it up:

-An unevenly worn tire has a different "surface geometry" then say... a new tire.

Say the amount of rubber on the outside of the tire was significantly more worn then on the inside. The angle of the tire to the ground will be slightly different than with a brand new tire, with indentical wheel camber.

Now if I set the wheel camber so that this unevenly worn tire exhibited constant surface temps across the width of the tire, I am accounting for both the altered angle of the tire in relation to the ground, and the heating factors that go along with both the altered geometry and the increasing lack of material/tread thermal mass from inside to outside edge.

When the new tire is installed, the tire may not exhibit even temps across (like the old tire did), due to the reasons I've just outlined. My question is to what extent do these factors effect the ideal camber? (The ideal camber being the one where temperatures are even across the tire, not the "IDEAL" camber... thanks solox).

Alternatively, to what extent will the temperatures across the new tire be altered?

....Does that make sense?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">....Does that make sense?</TD></TR></TABLE>

I think you fell off the wagon

 

Nah, but I am wondering where the hell all these ME's and self-proclaimed suspension gurus are at.... so to attract more attention to my incomplete and apparently illogically labeled thread, will you change the title to include one of the following terms:

beer
*****
H1


???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">include one of the following terms:

beer
*****
H1</TD></TR></TABLE>

Beer and temperature's effect on **** wear on top of an H1 car's carbon fiber hood?

 

That should do nicely.

 

I think that if you set the camber so that your contact patch is even to begin with, you won't get evenly worn tires. But I imagine that your point if having altered geometry on the tire would HAVE to change it's contact, thereby it's heat. But I would venture a guess it probably isn't worth setting up for, since ideally you are going to be putting on new feet eventually, and you would just want to set up that way.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gotocrx &raquo;</TD></TR><TR><TD CLASS="quote">I think that if you set the camber so that your contact patch is even to begin with, you won't get evenly worn tires. But I imagine that your point if having altered geometry on the tire would HAVE to change it's contact, thereby it's heat. But I would venture a guess it probably isn't worth setting up for, since ideally you are going to be putting on new feet eventually, and you would just want to set up that way.</TD></TR></TABLE>

I'm asking more theoretically then practically, but just want to be prepared since I won't be using new rubber initially.

 

why dont you re-evaluate the wear on your ***** with fresh rubbers on your probe?

I'm assuming you will have more than a one-time use of the pyrometer.

 

I'm gonna. Just thought I'd throw out a nice physics topic.

sack - who think ***** are way too expensive these days, and Pimp-daddy Toyo needs to toss some fresh new sizes on the street, of the short and fat variety.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">

I'm asking more theoretically then practically, but just want to be prepared since I won't be using new rubber initially. </TD></TR></TABLE>

Haven't I seen something about dismounting the tires and swapping them to the opposite side to "even out" camber wear (taking into account that you put the least worn portion of the tread section where it will get the most camber wear)?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">Gah... I was just trying to title a thread so as not to confuse the hell out of anyone.

I have not taken temps yet, in fact the camber kits aren't even installed yet.

Basically I'm just asking a theoretical racing physics question.... I guess I'm not being understood so I'll try and clear it up:

-An unevenly worn tire has a different "surface geometry" then say... a new tire.

Say the amount of rubber on the outside of the tire was significantly more worn then on the inside. The angle of the tire to the ground will be slightly different than with a brand new tire, with indentical wheel camber.

Now if I set the wheel camber so that this unevenly worn tire exhibited constant surface temps across the width of the tire, I am accounting for both the altered angle of the tire in relation to the ground, and the heating factors that go along with both the altered geometry and the increasing lack of material/tread thermal mass from inside to outside edge.

When the new tire is installed, the tire may not exhibit even temps across (like the old tire did), due to the reasons I've just outlined. My question is to what extent do these factors effect the ideal camber? (The ideal camber being the one where temperatures are even across the tire, not the "IDEAL" camber... thanks solox).

Alternatively, to what extent will the temperatures across the new tire be altered?

....Does that make sense?</TD></TR></TABLE>

oh, ok, i get it now. i'll take a stab at making myself look foolish.

i assume you already foresee that the new tire would show a temperature spread that indicates insufficient camber, ie hotter on the outside edge. since the tire is essentially "cambered" that makes sense. it would also make sense that the deeper tread depth of the outer edge of the new tire (compared to the old worn tire) would also squirm more and generate more heat as well.

determining the magnitude of the difference between old, worn, cambered tire and fresh tire with the same static camber setting is next to impossible though. the number of variables is astonishing. some quick ones that pop into my head are a reduction is "sliding" the car since the new tire has more grip, more body roll with new tires, tire pressure, tire pressure change, tire tread squirm, camber curves and the static camber being used.

it should also be noted that the worn tire would likely require a lower static camber setting then a fresh tire for many of the reasons stated above. a worn tire will also generate less heat total because of the lower amounts of tread squirm. again, determining the magnitude of change between them would require real time testing.

interesting topic. however, i think most people set their cars up with fresh(er) tires and aren't really concerned about the change in the temp profile from old tires to new, thus the lack of replies in your topic. that and the old addage, "tis better to keep your mouth shut and be thought a fool, then to open it and remove all doubt".

nate

 

Edit:I originally thought that you wanted to "get the most out of your tire grip-wise" but as I understand it now, you are trying to control wear on an older set of tires, and are asking how these settings will effect new tires?

I doubt that anyone has properly analyzed the maximum generated friction available from a tire at different tread depths (besides the manufacturer who probably won't tell you...). Since the molecular composition is altered (thus the friction) as you reduce the depth, you would have to integrate the friction of the tire across the thread (sideways), which would be a nasty function and an even worse integral. That's impractical anyway. You could sum up a few average values to make things nicer. However, I wouldn't know what kind of apparatus could do that especailly on a tire without cutting it into pieces, which ruins the tire.

Does anyone dissagree that a tire becomes harder (more wear resistant) as you remove material? I'll assume that the tires have been shaved, which defines the tread depth origin. I think that it's reasonable to assume that friciton decreases as tread depth decreases. Edit: I don't like what I said here before...so I'll change it...For an outer worn tire, the maximum friction the tire can generate is located on the inside. My reasoning is that it is imperative to keep the stickiest part of the tread on the ground. The effective width of this sticky portion is now smaller and has shifted towards the inside. With an evenly worn tire, you would want the tire to be flat under maximum cornering load. On the outer worn tire, you want the sticky portion of the tread to be flat with respect to the ground, but it is angled outward. This "ideal temp camber" setting will occur with slightly less negative camber because the outer will require more contact =&gt; friction to equal the temperature of the newer inside. So now your worn tires are set up with equal thermal temps under cornering load. Under braking, you will have accelerated inner wear. If you slapped on newer tires with this setting, you have less (-)camber than before, which means really bad outer wear.

Now inner wear is going to be heavily accelerated because not only is the inner portion of the tire is making more contact in a corner, but the inner portion of the tire has more grip, which means more friciton, which means more heat and more wear. Now you will have an inner wear problem. If your alignment was set to maximize grip on a new tire, the overall grip of the worn tire would be slightly less, but the wear would acceleration at a slower rate. It is a worn tire, though. You can't expect the same grip levels as a newer one. Unless you are going to be constantly changing settings (you probably will be), then you should set the car up to maximize a newer tire's grip.

I would not put as much stock into equalizing temps across a tire, especially since a tire wears under longitudinal and lateral acceleration.

Now I'm confused and I have to go to class (Thermodynamics I...hehe).


Modified by GSpeedR at 3:42 PM 10/1/2003

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">Your goal here is to maximize your tires' grip (using the traction ellipse/circle) and not to obtain wheel/suspension alignments that will "even-out" tire wear, right?
</TD></TR></TABLE>

Nope. Thanks for the post though.

 

I edited some stuff I didn't like above.

Question: How does surface temp correlate to tire wear?

Answer: 11.0

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I think that it's reasonable to assume that friciton decreases as tread depth decreases.</TD></TR></TABLE>

Well most say the RA1 gets stickier as they wear.

U of M?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sackdz &raquo;</TD></TR><TR><TD CLASS="quote">Well most say the RA1 gets stickier as they wear.</TD></TR></TABLE>

See that's the problem. All that molecular crap depends on the tire, among other stuff...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">U of M?</TD></TR></TABLE>

Yep. Transfered from Columbus, Ohio for engineering. I was a Buckeye fan, but I'd be killed by some Wolverines if anyone knew (as I type this in my CAD lab)...