tire pressure for track day

[cody]

Tomorrow is my first track day. I'll be running YOKOHAMA AVS ES100 215/45/17 on my 17X7.5" rotas.

Should I just up the pressure from what it says in the door jam for 17" tires by a few PSI?

Also, should I bother bringing tools?

[sperry]

Street tires will probably put on 5 to 7 lbs (maybe more if you're hard on the tires) when they heat up on track. If you want to run say 40 psi, set 'em at 35, and take it easy on track while they heat up (2 or 3 laps).

After your 1st session, when you come off track, immediately check the pressures, and set them where you want them when they're hot. You will of course have to re-warm the tires at the start of the next session.

[cody]

What should my target PSI be? 40 when warm?

[sperry]

Originally Posted by cody

What should my target PSI be? 40 when warm?

Depends on the tire (I've never tracked those tires), your suspension settings, the track temperature, etc.

My guess is that you want the hot pressure to be at or just below the max pressure as printed on the sidewall.

[Nick Koan]

Originally Posted by cody

What should my target PSI be? 40 when warm?

Tire pressures are a funny thing. I always ask questions like this at auto-x events, and no one gives me an exact number

The reason is, its a partially a personal feel. Higher pressures will stiffen up the sidewall, so the sidewall doesn't turn over while steering and turning. But too high will cause the tire to be looser then it optimum.

Not having run on the Yokohama tires, its even harder to hazard a guess. My only advice is to drive around the track and if your sidewalls are rolling over too much, add some air. If they are too stiff and the car is too loose, let a little out. More then likely, like Sperry said, is to start maybe 5-7psi more then normal. I generally run 35ish on the streets and will start at 38 cold. Watch the temperature after the run, and adjust down or up as necessary.

[AtomicLabMonkey]

I would shoot for low 40s hot with a typical street tire, as a starting point.

[MikeK]

I have had my tyres go up by 17 psi in a hard 20 minute session at RFR. The best idea would be to come off into the pit lane and check the pressures halfway through the session, then check again at the end of the session.

As everyone here has said, always set the pressures when they are hot, then take it easy for the first few laps to bring them up to temperature.

[sperry]

Originally Posted by MikeK

I have had my tyres go up by 17 psi in a hard 20 minute session at RFR. The best idea would be to come off into the pit lane and check the pressures halfway through the session, then check again at the end of the session.

As everyone here has said, always set the pressures when they are hot, then take it easy for the first few laps to bring them up to temperature.

Holy jeebus! Did you have any tire left after that track day?

'Course, you do drive a lot quicker than Cody will be, and I'm willing to bet that 17psi gain was on a hot day, no?

I'm gonna bet Cody won't put more than 10psi into the tires tomorrow.

[Dean]

Scott is right on. 35 cold, 40 to mid 40s hot, and always equalize left/right after a session, and ignore weirdnesss after that when cold. Hot pressures are all that matter.

Take some sidewalk chalk, or shoe polish and mark each tire in 3 places around the shoulder to tell how much you roll over. You don't want to go past the little triangles, but a light grazing up to them is OK.

Since it will be your first day, i won't bore you with more complex stuff. I'd just shoot to keep all 4 even when hot, and not rolling over teh fronts to much.

[MikeK]

Originally Posted by sperry

Holy jeebus! Did you have any tire left after that track day?

'Course, you do drive a lot quicker than Cody will be, and I'm willing to bet that 17psi gain was on a hot day, no?

I'm gonna bet Cody won't put more than 10psi into the tires tomorrow.

The first SCCA track day. It was stinking hot. I started at 35 psi, and ended at 52 on my front right. By the last lap I was sliding everywhere.

[MattR]

Originally Posted by MikeK

The first SCCA track day. It was stinking hot. I started at 35 psi, and ended at 52 on my front right. By the last lap I was sliding everywhere.

Yeah, Ditto for me , in that same track day, we ran back-to-back sessions with a 5 minute break, and my right front was up 15 lbs from where I started. (r-compound ADVANs)...

Those Yokes Cody should only come up about 5 to 7 lbs during the run, like everyone said.

[cody]

Thanks all. I had only read Scott's responses before I left, but these tires have a max capacity of 51psi. I decided to go with 38.5 in the front and 36 in the rear. This was after driving on the freeway for a couple miles, but I'm going to assume the tires were "cold".

Does that sound okay to start? I'll definately check them after/during the first run to see how they do. Thanks for the chalk tip Dean...I always wondered what those triangles are for.

[doubleurx]

Originally Posted by MikeK

The first SCCA track day. It was stinking hot. I started at 35 psi, and ended at 52 on my front right. By the last lap I was sliding everywhere.

Heck I was sliding on the second lap (probably one of the only times I was in front of you Mike).

[sperry]

Originally Posted by cody

Thanks all. I had only read Scott's responses before I left, but these tires have a max capacity of 51psi. I decided to go with 38.5 in the front and 36 in the rear. This was after driving on the freeway for a couple miles, but I'm going to assume the tires were "cold".

Does that sound okay to start? I'll definately check them after/during the first run to see how they do. Thanks for the chalk tip Dean...I always wondered what those triangles are for.

That might be a little high. I was assuming a max pressure in the 40-45 range... just because the tires will handle 50+ doesn't mean that's where the traction is.

Starting at 36f/34r cold is probably more realistic. If you get out there and unintentionally over-drive the car, you'll put a lot of heat into the front tires very quickly. You can always adjust the pressures after the 1st session.

[cody]

Cool, lowering it doesn't cost 50 cents like raising it did.

Thanks for the advice.

[sperry]

Originally Posted by cody

Cool, lowering it doesn't cost 50 cents like raising it did.

Thanks for the advice.

Someone will surely have an air tank out there if you need to go up a bit.