I am looking for advice regarding tire pressures on track days. I am running at Auto Club Speedway in Pomona, CA The tires are Yokohama ADVAN Neova AD08s.Speed at the end of the straight should be in the 140+ MPH range.
Car has a track suspension, big brake Wilwood kit, 5.0 Ford 280 RWHP. Ambient temp should be in mid to high 70's. I would appreciate any and all advice. Thanks.

 

I would ask one of the instructors or guys that have spent a lot of time on that track what their thoughts are. I don't think you would see much difference on the straight away between a few pounds either way. Trail braking from 140 into turn 1 is quite another matter though and you want all the grip you can muster of of them. You may have to keep trying settings till you find the best grip for your car on that track.

For what it is worth I like to shoot high then back off after the first session as things warm up. The track I run I usually put a few more pounds in the right then the left due to a high g turn that puts a lot of pressure on the right side. But your set up and track is so different from mine I can't really give you a number. The old chalk on the side wall thing and reading inside to outside tire temp works pretty well to see how your tires are doing.

I hope you have a really great and safe day at the track! Let us hear how it went for you.

 

Have you ever had it up to 140 before? I only have a chin spoiler, small rear spoiler, side skirts and a hardtop and anything over 130 gets a little too close to "takeoff" for my tastes. Believe it or not, hood vents made the biggest difference in high speed stability.

Remember that the pressure the tires are when you leave the pits will be very different than the pressure they are when you pull back in. Start at 30 or 35 psi and then check your pressure as soon as you pull back in. You probably want 35 or so psi when hot.

I am by no means an expert or even an authority of any type on this. Morris West is a member here with a lot of V8 track experience. He, as well as a few others would know better than I and will hopefully check in.

I'd recommend Hawk Blues for those tires BTW. I ran Hawk blacks last time with RS3's and the brakes were out braking the tires (a very disconcerting feeling). I also have Wilwoods on mine and a stiff suspension.

-Jason

 

Jim, Thank you for your response. I wanted to wait until the dust settled at CA Auto Club Raceway "Fontana" before reporting back. Temp was 65 all day. With wind. The instructor kept me under 100 MPH for two sessions. Tire temps went to 38lbs. Tire wear and temps were fairly even across. third session saw 130 mph, which was plenty on the banked part or the course. When I bought the car, It looked like a real poser. (see 302 Miata pics from previous owner) 245-40-17's on the rear, 235 front. Happily I was wrong. Handling was amazing. Saved my rookie driving skills several times. Will try again in a few months. As part of car prep, I had it corner balanced and aligned for aggressive street. In case others are wondering, car is registered to my AZ address because of CA CARB regulations.

 

Jason, I will be using Hawk Blues next track day. Saw strong fade off banked straight, however the Wilwood front big brake kit cooled quickly with no residual effects. Tires held steady at 38 lbs. Had a little sidewall roll at right rear. Next time I want to collect more performance information, I.E. G;s, accelleration, etc. Thanks for you great input