Proper Tire pressure for track day?

[mousewei84]

Hi guys! So I just got new set of tires and wheels and ready for coming track day. It is 275/35/19 96Y Michelin PSS compare to OEM 255/35/19 96Y XL Dunlop SP SPORT MAXX GT. So OEM suggested pressures are 41/38 for full loaded car and 38/32 for normal load condition. I am wondering if the change of my tires and sizes would affect standard tire pressures? There are width change(255 to 275) and load index change( XL to nothing). Also personally i don't know if it is gonna be a problem if load index XL is gone. Currently it is 43/39

Also I plan to track those tires, in your experience, what is the proper track tire pressure for Michelin PSS tires?

Car is 14 S5. Thank you for you help!!

[dazed1]

All depends on the track, driving style, track temp, ambient temp, how hard you push and get the temps up, etc. Too many variables.

Start with door temps and then work your way up / down based on how tire temp + pressure change & feel.

[xuandatou]

I had some track events with my 13' S5 with 275/30/20 Michelin PSS , normally I would set it down to 34F 33R (cold) before my first session, and release a little bit if necessary (set 40F 39R when hot) after the first session. Then it would be good for the rest of the track day.

I would suggest you measure the pressure for all 4 tires before and after each session (just be safe)

[mousewei84]

Thank you! Temp would not be high since winter is not over yet. So work your way up is better compare to work way down right?

All depends on the track, driving style, track temp, ambient temp, how hard you push and get the temps up, etc. Too many variables.

Start with door temps and then work your way up / down based on how tire temp + pressure change & feel.

[mousewei84]

Thank you for your input! One question, since your front and rear pressure are close, do you feel more understeer? tire rack suggest high front low rear to reduce understeer.

I had some track events with my 13' S5 with 275/30/20 Michelin PSS , normally I would set it down to 34F 33R (cold) before my first session, and release a little bit if necessary (set 40F 39R when hot) after the first session. Then it would be good for the rest of the track day.

I would suggest you measure the pressure for all 4 tires before and after each session (just be safe)

[xuandatou]

Thank you for your input! One question, since your front and rear pressure are close, do you feel more understeer? tire rack suggest high front low rear to reduce understeer.

You would experience understeering anyway

Unlike R-compounding tires, PSS is not very sensitive to pressures, but according to my own experience, 40F39R setting (when hot) grips the best and do not forget to leave your ESP at the Sport Mode

[VicS5]

I agree with these target pressures hot at the end of a session. How low you need to start cold to end up at these pressures hot depends on all of the variables listed by dazed1. I start 33f/32 r during summer at Watkins Glen for first session, the adjust to reach targets. Usually need to change over course of day as track and air heat up.
Too little pressure up front and our heavy cars will cause rolling over onto shoulders of tires; to much and things get squirrelly.