Tire Pressure for Bridgestone RFTs at HPDE event

[OLEK135i]

I am participating in a HPDE at Putnam Park this weekend and was hoping for some advice from my fellow 1ers. I am running completely stock and was hoping for advice on what tire pressure I should run. It is supposed to be partly sunny and in the low 70s this weekend at the track. I have spent time on the forum but found no specific information regarding the the OEM Bridgestone RFTs for HPDE events. This is my second event and I never bothered checking my air pressure before, during or after the first event (I know, dumb, but I had 3,000 miles on the car). Eventually I will switch tires sometime down the road, but for now I am keeping everything stock including tires. I have just under 6,000 miles on the car. Thank you in advance.

[MarkR171]

I was running ~40 front and rear and had some wear on the outer edges, might be good to try running more pressure, though short auto-x runs are a lot different from track days.

[OLEK135i]

Thanks MarkR171. Anyone else?

[TrojanBMW]

Originally Posted by MarkR171

I was running ~40 front and rear and had some wear on the outer edges, might be good to try running more pressure, though short auto-x runs are a lot different from track days.

I would shoot for 40 PSI front and rear when the tires come off the track hot. Checking the tires is the first thing I do, when I get off the track, and 40 PSI seems to be the sweet spot for a 30 minute session. Any higher and the tires get too greasy, lower and they roll on the sidewall too much.

There's not much you can do to keep the outer edges from wearing on the track. It's just the nature of the stock suspension.

If HPDEs become a habit (and it will), I would use the weekend to burn up your tires, and replace them with a set of non-RFTs.

Then you'll want to do some camber plates, and coil-overs, then some track wheels, etc, etc, etc. . . .

[LA-Bimmer]

I agree with about 40psi hot (after session) for those tires. Likely will have to start around 33-34 before getting on the track. May have to adjust across sessions to find the best fit. Talk with your instructor, that is part of what they will help with. I'd also use a piece of chalk and make a line on the sidewall from about 1.5" below where the tread starts up onto the tread. After the run you can check it to see where it is rubbed off and that will give you an idea of how much roll onto the side wall you are getting.

[OLEK135i]

Awesome, thanks for the help. So I should inflate around 34 psi prior (cold) and if I come off after my first session and I am not at 40 psi, simply add the amount missing and continue to monitor after next session. Never thought of the chalk. Thanks!

[TrojanBMW]

Do yourself a favor and buy a nice tire gauge before heading to the track.

[pjdvd]

I've been running for only a few months now (AutoX) and I've been inflating to 40 front and rear. Only one lap at a time so I don't build much heat. I ran at stock pressures and then felt so much better at 40 all around. I've fiddled with 38 in the rears but I still think 40 is the way to go. I only make it up to 43 max after 4 runs 8-10 min apart. 55 sec runs. I've chalked the tire and never gotten close to having too much roll.

Non-RFT's next. prob star specs.

[pixelblue]

it really depends on how hard you push the car in the corners but I agree with 40 upfront and 38 rear. again depending on how hard you push you should start with 5 lbs below those points and just monitor after each session

[OLEK135i]

Thanks for the advice. An instructor at the event had 135i as well and recommended I set the pressure once and monitor for the day. I started cold at 33 all around and after each session was around 40 ish for all the tires with the left front the highest at about 42 and the right rear the lowest at about 39 (Putnam has a lot of right turns with turn 1 a sweeper that I enter after acheiving around 125 mph or higher, turn 7 essentially a 90 degree turn which you need to decelerate to about 30 mph before entering and turns 9 and 10 essentially being one long double apex turn at very high speed [can't remember exact speed but assuming around 60 during the turn?]) Outside temp was cool (60s) both days sunny on the first cloudy on the second. On day 2 I had to inflate both rights as they were down to 31 cold prior to getting on track. I figured I'd share in case someone decides to HPDE on the Bridgestone OEM rfts.