When I went with an M, the guy running it (racing instructor) suggested that we pump up to 45-50psi! The car seemed to stick really well, but I have to admit I also thought that was high!
I have the same question but I have 330i w/ Sport package. Street pressures are 39 front and 46 rear. I have tried 39/40 hot with ok results. Tires are 225/45-17 front and 245/40-17 rear. I have the original conti's on the car. Thanks
I'm at 36 front and 39 rear. I'm not 100% satisfied with the handling though.
I'm debating on trying the chalk 'trick' to see if i need to bump the pressure or not.
You guys have any suggestions?
EDIT: I should mention why I am not 100% satisfied. The oversteer on the car. 41 psi was too much pressure (according to the arrow on the sidewall - if you don't know what I'm talking about, I'll explain). now 38-9 and I feel the ass is even more loose than before, but the arrow indicates that the pressure is perfect.
Buy a pyrometer (about $100) and check the pressures (outer, middle, inner) on all four tires when race-hot and you will know how the track and your tires work together. Too much pressure makes the tire bow out in the middle so the middle will be hotter. Vice versa as the edges will be hotter for not enough pressure. The works better than chalk, but there is nothing wrong with using chalk.
Write everything down when you measure the temperatures so you can make the 12 measurements quickly, as soon as you stop racing, and so when you look back at the course you can correct for left or right corners predominating.
You can also set camber with a pyrometer but sometimes too much toe makes the numbers look odd.
This is what I will do, although it can be a bit time consuming to unbuckle the harness, disconnect all the helmet wirings, climb out of a seat bucket, rush to the tires and start the manual logging process. During the process the tires would have cooled. But data still helpful nonetheless.
Unless one has pit crew.
Tom Busby said:
Buy a pyrometer (about $100) and check the pressures (outer, middle, inner) on all four tires when race-hot and you will know how the track and your tires work together. Too much pressure makes the tire bow out in the middle so the middle will be hotter. Vice versa as the edges will be hotter for not enough pressure. The works better than chalk, but there is nothing wrong with using chalk.
Write everything down when you measure the temperatures so you can make the 12 measurements quickly, as soon as you stop racing, and so when you look back at the course you can correct for left or right corners predominating.
You can also set camber with a pyrometer but sometimes too much toe makes the numbers look odd.
This is what I will do, although it can be a bit time consuming to unbuckle the harness, disconnect all the helmet wirings, climb out of a seat bucket, rush to the tires and start the manual logging process. During the process the tires would have cooled. But data still helpful nonetheless.
36psi front, 33psi rear for me (cold).
running PS2's - 235/35 19" front and 245/35 19" rear.
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