Hola,

Doing my second track event at Thunderhill next week and was curious what are good psi values for front and rears.

During a few hours of spirited driving I am usually at 40psi rear and 34psi front.

But last time I was on the track the rears got up to 46 psi, way too high. It would also be nice to know how much I should deflate the tires before I start warming them up so I don't have to make a pit stop later when they are hot.

Thanks for any info!

 

I found 38/42 Hot to work well yesterday for PS2s. 50 degrees and mostly sunny, 1:04s at Lime Rock in Black run group. Optimal operating pressures for the PS2 from my old research was 42 PSI - so I worked from there and backed down 4 PSI for the fronts.

 

You could try filling them with nitrogen for your next track day; it doesn't tend to expand as much. I personally run at around 36-7front / 43-4back (hot).

 

Guess what - that was WITH nitrogen, which my dealer put in no charge at delivery. What a farce it was for me - my left rear went up 11 PSI!

All sarcasm aside - thanks for suggesting Nitrogen, but I found there to be no difference in swing in PSI over normal air on street or track. I guess the real benefit is lack of water molecules which can degrade the tire and valve stem over time...

 

Really! Guess the extra 10$ I paid was useless ..

Then the only real benefit would be to make sure you check the pressure with a accurate Tire Gauge .. the TPMS sensors don't always give you the best reading. I usually fill up my air; go for some laps then check the pressures again (and change them based on the track).

 

Yah, I only use the TPMS to look for dramatic suggested change on the street - not really any time on the track to squint to see those tiny TPMS numbers while at 10/10ths.

I use my best guess at the start of a session and then adjust as soon as I come in. Track time is so precious I don't want to pit-in and lose 5 minutes (between slowing to pit, the pitting process (5 mph in the pits), checking / adjusting, then 5 mph to the pit-out, then waiting for a gap...

 

I lap in 20 minute intervals (on/off) .. after the cool down I check the tires. If you think changing pressures are annoying .. try adjusting the camber while pitting!

 

Ok thanks for the info! If they have nitrogen readily available at the track I might give it a shot.

 

From my experience with and without Nitrogen, I'd avoid it. I joked with my dealer when he comped me when I picked up my car - "So, do you have any Nitrogen-in-a-can that I can bring to the track with me?" It's impossible to work with a product that's not readily available... And, as I found, it made no difference and even if it did, then I wouldn't be able to share pressure data with 99% of the rest of the world that doesn't run Nitrogen.

 

For DE's nitrogen is not worth it because you will not run the same pressure for the track and for street everyday driving.