If tire wear is a factor, like if the track is particularly abrasive, super-cooling the tires like that will harden them and keep them alive longer.
I know a few tracks we’ve been to where tire wear was so harsh that if you weren’t careful you would wear them down to the canvas in a day of racing, so there were a few teams that were supposedly giving the tires an ice bath after each session. The legality of that would vary depending on the organization, but as far as I know, that was legal in those instances.
I don’t have a TKART subscription anymore, but I remember reading an article from one of the tire manufacturer’s that recommended this. Hence my comment above. If someone does and wants to find it the article to share a screenshot.
I guess the idea is on hot days it might buy you an extra couple laps before the tires roll over into too hot territory? Makes sense in that they would “thaw” as you get going. Someone needs to science this.
As context, for this race IAME X30 Shootout at GoPro, it was a totally different format. There were 4 sessions — race was at night and I think the temp was in the low 60s, maybe even the high 50s. Also, the whole thing was run on a new track layout that no one (?) had driven previously.
Practice (roughly 10 mins)
Heat 1 - 10 laps
Heat 2 - 10 laps
Final - 15 laps
I believe there were about 15 minutes between sessions to work on the kart and then back out. Possibly the tires would not cool completely between sessions and that is why they used the ice bath? Or they knew there would be no effect but they wanted to give us punters something to talk about.
As for the human cold water bath — yes, very nice and enjoyable.
Rapid heating and cooling of the tire hardens it. You’re accelerating the heat cycle. It’s not about starting the tire colder so keep it from overheating. You actually harden paint the same way. I bake every layer of paint at about 130°F and then cool it with a fan. Helps accelerate the evaporation of the solvents and allows much quicker dry time.
Paul’s point about the very short time between sessions is probably the situation in this particular instance. You don’t want to carry over the residual heat into the next session and accumulate heat in the tire, effectively leading it to overheat by the second or third session.
Semi-related, but we ran tire warmers for a fun race once when it was about 30°F out. Super-heated the tires up, and then set the pressures. They lost about 3 psi just pushing to the grid, our out lap was the fastest, and the tires cooled and got progressively slower every lap. Came in and the tires had lost about 7 pounds of pressure over the course of the session just from the temperature differential.
Seems like this process would play hell on setting your tire pressures at the start of the next run. Since temperature affects pressure, you are effectively lowering the starting pressure. From my understanding of setting tire pressures, the lower the starting pressure means the tire takes longer to come up to temp and ideal grip. Good for a long Main.
Conversely the higher the starting pressure, the faster the tires come up to temp and ideal grip, but can fall off/overheat faster. Ideal for short qualifying sessioin.
For an Ice Bath to work effectively, you would have to have the tire’s temperature and pressure at a known value prior to chilling them, as well as a target temp/pressure to stop cooling them or when they begin to warm up they will be out of their working window.
Also, with only 15 minutes between sessions would the tires have enough time to come up to ambient temp before hitting the track again? I guess if it just a quick shock, then they would not be as affected as if they were giving a longer soak. Otherwise you might damage the sidewalls from running the tire underinflated at the start.
Just some thoughts from dealing with Cars and Weather Changes. Its always a head ache when the air temp drops and everyone comes in panicking because their low tire light came on.
I know some serious/competitive autocrossers use simple garden pump sprayers to cool their tires with water between runs on hot days. Maybe the same tool could be used if you wanted to cool your kart tires.