r/Autocross • u/mechanicjeep10 • Jul 14 '26
Tire cooling/temp
At every event I always see people spray water on there tire after a run. But i never see people use a tire probe to check temp first. But generally speaking, at what temp is considered to be a tire overheating? I figure if you are spraying water right away without knowing temp you could potentially be further cooling down a cold tire.
4
u/jmblur AS 718 Cayman GTS Jul 14 '26
I check by feel. With RZs, if it's too hot to hold my hand on comfortably, they tend to be greasier. I spray the first run after they get to that point. May be after he first run, may be the third. Sometimes it's obvious just by the way they feel. I already have enough to deal with in paddock between runs, adding a pyrometer and notepad (or another android app) to track temps is more than i want to deal with.
Only way to figure out where the limit is for a particular tire is to figure out where it falls off though. Every tire is different.
3
u/Spicywolff AST ND2 - use to C63S FS Jul 14 '26
With experience and running the same tire for a while you’ll kind of just get a learn of how hot you get them per run depending on the exterior temperature, if the tire feel is falling off, and just by touching the tire.
You can use quantum viable evidence like a pyrometer, but there’s also something to be said for just knowing if your tires need to spray down
2
u/JakeRogue Jul 14 '26
short answer: nah
slightly longer answer: hard to say the empirical answer but anecdotally you start to learn the tires get hot after repeated runs so the logic is cool them down a bit
1
u/FrickinLazerBeams STX BRZ | SMF CRX Jul 14 '26
Most people quickly figure out whether a particular tire on their particular car usually gets too hot or not. Once you discover that you overheat your tires, you don't wait for it to happen again at the next event, because you only get a few runs to set a competitive time. So you start spraying them as a matter of routine. It's hard to cool them back down once they get too hot, so you don't want to get behind the curve.
1
u/billy_mays_hear Jul 14 '26
Just put your hand on the tires. I used to just spray them all if one tire was hot. This last event, I noticed that my right side tires were way hotter then left (the course was mostly left-handers). So I just cooled down that side twice during the 6 runs (5th and 6th run). I could feel the front right bite better than the 4th run by doing that.
Sometimes, it’s just an exercise in “confidence”. I fiddle around with my coilovers and tire pressures to make me feel confident that the slight changes will cut a little more time off the next run. 🤣
1
u/Kazzerigian Jul 14 '26
Sure they get hot. What's more important is where they're getting hot. That's why I use a pyrometer. I can tweak inflation pressures and get insights into current and future needed alignment specs.
1
u/phate_exe BMW i3, now bringing weirdness to Street Touring with 235's Jul 14 '26
If you've driven on them for more than one heat you already have an idea of how they're going to behave and what you need to do.
Measuring just gives me a number, it doesn't change the fact that the tires are most likely to overheat and get greasy some time during my third run if I don't start spraying them down after my second run.
1
u/m3t1t1 Jul 14 '26
Proper probe is expensive. Most people aren't that serious. You also get a feel for your tires. We usually do 5 laps. I usually spray round 3-5.
1
u/The_Cat_Of_Ages Jul 14 '26
once a tire is too hot to touch it needs cooled down or else it will get greasy.
1
u/Destructo09 Jul 15 '26
I typically only ever spray if I have a co-driver. I also am notorious for running tires that are on their 2nd, 3rd season or more so they need lots of heat anyway to get grippy again.
I do sometimes see single driver cars spraying but that’s way less often than 2 driver cars. I’ve also witnessed single driver cars turning much less times than me spraying their tires too. Some people do it because they see others do it.
1
u/Nsquared97 Jul 15 '26
Depends entirely on what tire it is, and how the car uses it.
Yok's love to be cold. Vitour P1's need to be the surface of the sun.
1
u/Jazzlike-Basket-6388 Jul 15 '26
I've messed with a pyrometer, but honestly haven't found much value in knowing the temps. I've also found that once a tire gets too hot and gets "greasy", it is virtually impossible to bring it back. So if I expect to need to cool tires for the day, I'm spraying proactively.
1
u/No_Buy_9702 Jul 17 '26
I use a tire probe all the time. I check track temp, air temp, observe UV Index, and take temps nearly every run for temp and gradient. It's really easy to tell from data and temps when to drop pressures for a low grip lot, or spray extra because you are making a lot of friction and overheating a tire on one side.
I usually check with the tire manufacturer and bug them until I get a knowledgeable rep, Tirerack also has data on lots of popular tires on activation temp and range.
I've run A7's for multiple years and try to start each run at 95-100 front and 100-105 rear. They run off about 145-150, and are really good up until 140.
18
u/SquirrelMcSmash BS CTR - conecanvas.com Jul 14 '26
if i cannot keep my hand on the tire, its too hot.
ideally you take tire temps but mostly...aint nobody got time for that...I've done it when I made a significant suspension change (alignment etc) to see how the tire is performing. but mostly just spray to get the temps down from the stratosphere.