Tire temps, For you track driver/racer types Options

[campbellcj]

OK, I know that the general concept of tire temps (pyrometer reading) is you want to check your alignment and suspension setup by looking for even or "logical" temps across the tread of the tire (outside, middle, inside) and also from front-rear and side-side.

Is there good detailed write-up somewhere explaining what different flavors of temp readings mean and what to do about it (corrective action)?

Also, what is considered a good operating temp for typical DOT-R tires like Kumhos? If your tires are "cold" or "hot" compared to what is the desirable range, what does that really mean (corrective action)? In other words if I have even temps, but low 100's instead of upper 100's or low 200's, does that mean I should just push harder in the turns, or what?

Mildly Confused,

[Dave_Darling]

I think there are enough variables in the exact temp readings that shooting for specific temps isn't going to get you anything.

What you really want is to have even temps across the inside, middle, and outside of each tire. Higher temps in one spot mean you are "working" that area of the tire harder, and lower temps mean you aren't working that part as hard. You want to spread the work across the whole tread surface of all four tires.

If the middle of the tire is hotter than the inner or outer edges, the tire is probably overinflated. (I say "probably" because tires with very stiff sidewalls can actually exhibit this from tires that are underinflated; the middle bulges out from centrifugal force or some such.) If the inner edges are warmer, then you are riding on the inner edges of the tire too much and you need to dial some negative camber out of the alignment. If the outer edges are warmer, you're riding on those too much and you'll want to dial in more negative camber.

Front versus rear temps can give you an idea if the car is understeering or oversteering in general. Again, you usually want it pretty close to even. Side to side temps are usually not that useful, because we can't generally do that much to affect the left versus right side loading. It's usually a factor of static weight of the car, and the way the course runs (mostly left turns or mostly right).

--DD

[drew365]

Chris; try www.elephantracing.com/techtopic/tiretemp.htm
They have a basic symptom/diagnosis chart thats helpful. I've been told 180o is a normal track temp. 200 is too hot.

[campbellcj]

Thanks guys. Last time at the track, I took some temp readings and they were quite even across the tire and front-rear (which is good). This was a clockwise track so the lefts were hotter than the rights, which is also logical. But the temps seemed low to me (I didn't write them down, shame on me)...lower 100's I think. My car is quite light, and there is not a lot of heavy braking on these tracks, so I know that accounts for some of it.

I'll check out Chuck's write-up later tonight. Gotta get the car ready for tomorrow (heading out at 5:30am...ick).

[Zeke]

Depends on the brand and the model of the tire. Some tires "come in" sooner. The manufacturer should have a data sheet for recommended camber settings and optimal tire temps. This has to be true because at too high a temp, the tire will blister. Before the tires blister, they should feel greasy on the track. But if only one portion of the tread is getting real hot, you won't notice it that much in the handling. You need to get the alignment right before you push it too hard. This all IMHO.

[AARRGGH]

3 hot laps at Willow Springs, after warmup, 2200 lb car on 8" goodyear gumballs - 170 - 180 degres.

Sorry, forgot to add, Nitrogen filled.

[Don Wohlfarth]

Tire temps can tell you more than you want to know. (IMG:style_emoticons/default/wink.gif)
Use a probe type pyrometer and take 3 readings per tire, inside, middle, outside.
Try and do measurements exacly the same way everytime, LF, RF, RR, LR, or whatever, just do it the same everytime.
The most important part: Write every temp down. The more you write the easier it will be to find out what is happening tire wise. Ambient temp, overcast, bright sun, etc. If you're running de's for 20 min try and have several hot laps and come in after 18 min with no cool down lap. Take tire temps on the hot grid if possible but take temps in the same location everytime. Tires will cool down very quickly. You want to be able to have a repeatable way of doing everything. It is not helpful to have one set of readings after several hot laps from the hot grid and another reading after a cool down lap and back it the pits.
It will be very difficult to have the same reading accross the tire with DOT R type tires. Best guess is 170-165-160 inside out would be damn good. If you had 170-170-160 let out 3psi. If you had 180-165-150 you would have too much neg camber.
If you can't get temps above 150 you are not driving hard enough (working the tire) or you have too much tire under the car.
You may find that you have one front tire, say RF, that is 10 degrees or more hotter than the LF, as the track you are driving has more left turns than right turns.
You also want to take and write down tire press AFTER you take tire temps.
Always work with hot pressures. You will find that your tires pressures will rise 6-8# from cold to hot (not warm to hot). You are trying to have the same hot pressures when you come in from hot laps when you start taking tire temps.
All of this is general assumptions to get you pointed in the right direction.
Aren't you glad you asked? (IMG:style_emoticons/default/biggrin.gif)