I'm pretty new to track driving, having had only three track days before last Thursday, all on warm days on warm tracks (at least 65 degrees F). I never had a problem with traction, or feeling my rear end loose (unless I made a mistake). Last Thursday, I had a track day on a very cold day--it certainly never got above 50, and probably spent most of the day near 40. I was driving as fast as I had on my previous warm weather day, but I was working much harder to keep the rear end in line--it felt "greasy" the whole day, and slipped out on me a tad several times, something which had never happened before on the track (autocross, yes). Nothing else was different--same car, same setup (including tire pressures), same track, and same tires. The tires are worn, but still street legal, and the track was dry.

Is it likely that this was an issue with these tires on a cold track? If so, is this a problem with any tire on a cold track, and just worse with these?

Thanks for your thoughts.

 

When/how did you measure the pressures? If you measured them cold, then you likely had too much pressure once they were up to temperature, which will definitely get a street tire greasy fast. Always measure temperature/pressure in the hot pits after a hot lap for best consistency.

 

All tires are effected by heat, and yes certain tires like soft performance tires can be very un-sticky in the cold, but not all soft tires are effected negatively in the cold because if you take something like a true snow tire, their rubber compound is very soft, that is what allows them to grip/bite into the snow.

Be it S-02s or RA-1s, a cold tire will not give you the grip potential a warm one has, and if you go beyond that "perfect" operating temperature and get them too hot, they too will have less grip. How the ambient temperature affects your tires is a very important lesson to learn. Let me guess, you have never ridden a motorcycle in the cold...

 

I know several other people who were at Proformance with you on Thurs, Mark. They told me the track was really slick that day. I'm not surprised it felt slick to you.

When PR is cold/damp it does get very slippery. Especially the lower part, which gets very little direct sunlight.

 

Each time I have tracked the car, I have increased the pressure at home, on cold tires. Both this most recent time, and the previoud time, I increased the rear tires to 5psi over spec, and the front tires 6psi over stock. I am going to get a pressure tank so I can play with the pressure hot off the track; what should my pressures (on a MY04) be hot off the track?

Mike, thanks for that report, it makes me feel better. It also makes me a bit leery of doing another track day before it gets warmer, at least at PR.

 

Set it the way you have been, go out and warm up the tires, come in and measure the pressures. Adjust from there. Maybe kit has some idea of pressures for an 04, but you'll have to experiment to find the right balance for your car, track, conditions and driving style.

 

This might not apply to you, but I've found that high-performance tires become hard and slippery after they've gone through enough cycles of hot/cold. How many miles do these tires have on them?

 

Guys, I'm telling you: Mark's tires might or might not have been at their best, but the most likely reason why the track seemed slippery is because the track really was slippery. Just something we have deal with up here in the land of the rain and the moss.

 

PR is a total mess when its cold, I think Mike is on the right track. The backside is a nightmare because the trees mask any sunlight. The track surface is seldom reaches ambient temperature. I think ambient crept up to the low 40's that afternoon.

However Mark, you should be checking your pressures with a gauge and chalking the tire to determine utilization. Check your pressures after each session upon returning to the pits. The vast majority of track days, you will be putting heat into the tire. Unless the ambient temperature drops during the day, you have no need to add air to the tires. You can use a grease pencil or chalk to draw a line across the tread and onto the sidewall for all of your tires. If the line is rubbed off the sidewall, you *generally* need to run higher pressures. If the line does not wear fully from the tread block, then you need to decrease air pressure.

 

I thank all for your helpful responses, especially Mike and Jerry. I understand what Jerry is saying about chalking my sidewalls; I'll get a pressure tank before my next track day (which likely won't be before April or May, given the slippery nature of the track until it next sees the sun), so that I can raise or lower the tire pressure, as seems necessary; I'll also get better tires (some sort of track specific tire, which still will be legal for stock autocross) to use only for the track, but the big lesson seems to be that our local track is just slippery in the cold season (which, unfortunately, lasts 7 or 8 months around here).