[rphz]

I've got OEM 19" 442M staggered and I set them at the door recommended 35/38 psi. Last time I was at the dealer, they set them back to 32/34 which seemed odd

[BimmerF32_430i]

Originally Posted by Musashi

I almost arrived at the same figures on my new 235/40 19 and 275/35/19. Lowered to 32 front, and the car became really moody, and mushy. Very much so. Temps here, 13C, so 60? But my 335i M Perf is also 3690lbs, with Adaptive M tuned for hard 20" Pirellis. At 35F 38R I seem to have OK results. however, have yet to run them a really warm day pass 75F, just got them! But 32 front was surreally mushy.

I set mine to 35F 38R since and I definitely think it's better than what I had it previously

[zole2112]

my car guy, used to tune BMWs, did my wheels/tires, he put in 44psi all around, his recommendation. so far its great, I would have went with the door sticker pressures but his guy is good...I think ahahha

[BMW11]

Originally Posted by zole2112

my car guy, used to tune BMWs, did my wheels/tires, he put in 44psi all around, his recommendation. so far its great, I would have went with the door sticker pressures but his guy is good...I think ahahha

seems that 44 psi is a bit too high. what wheel and tire size is it and what does the plate on the car door say and what is the Max psi on the tire say? is it 44psi cold? and then when hot it may approach too close to the Max pressure. is this for everyday driving (the 44psi) or is it just for the race track? does anyone else here use 44 PSI on their BMW 3 series?

[zole2112]

Originally Posted by BMW11

seems that 44 psi is a bit too high. what wheel and tire size is it and what does the plate on the car door say and what is the Max psi on the tire say? is it 44psi cold? and then when hot it may approach too close to the Max pressure. is this for everyday driving (the 44psi) or is it just for the race track? does anyone else here use 44 PSI on their BMW 3 series?

I agree that it seems a bit bit too high, I'm going to change them to what is recommended on the door plate.

I am running 255/35/19 on all 4. I have been using the 44 psi for everyday driving for the past 2 weeks.

I have 2 different stickers in the door, one is the standard white one for the std tire size which shows 32 front and 38 rear. In addition I have a yellow BMW sticker that states 39 front and 46 rear.

[rphz]

In looking at the manual for my F32 (pdf I found online), there are very specific tire pressure recommendations for various models in the series (428i is different than 435i), tire type, 18, 19, 20" sizes, with/without "high-speed tuning feature", and up to 100mph and over 100mph tire pressure ratings.

I don't think zole2112 is too far off (though maybe 2-3 psi above the recommended settings) depending on driving style and comfort level. I tried the recommended 39/41 for my F32 and they were a bit harsh on bumps/pot holes. I'm a little concerned of a possible higher risk of blowout (non-rft) at the higher pressures.

[Musashi]

Originally Posted by BimmerF30_335i

I set mine to 35F 38R since and I definitely think it's better than what I had it previously

Ack, with the latest Dinan Sways and Springs, less roll, more tyre effort. So the extra grip I have in the 235/40 19 275/35 19 and less roll results in rubber heating faster. Nice side effect. When trying 35F 38R at 25C it becomes rapidly 39-40F 44-46R. Car bounces, rear can slip. Have you experienced this?

I use a digital meter. More so as when I tried inflator gauges, analog gauges, they vary as wildly as 6-10PSI. The digital seems rock solid. In addition, I also use the good old chalk method. But these tires are so temperature sensitive. So 32/35 at 11C becomes 33.5 / 37.5 at 25C, and 4-6 PSI more driving.

[Musashi]

Originally Posted by zole2112

I agree that it seems a bit bit too high, I'm going to change them to what is recommended on the door plate.

Am running 255/35/19 on all 4. I have been using the 44 psi for everyday driving for the past 2 weeks. Ihave 2 different stickers in the door, one is the standard white one for the std tire size which shows 32 front and 38 rear. In addition I have a yellow BMW sticker that states 39 front and 46 rear.

It actually varies with tyre model. When the Bavarians give us the car the PSI is tested in and out on track, not the least Nurburgring. Catch: my car came with 20" 225/35/20 and 255/3020 Pirelli RFT. Recommended was 38F 44R. On warm days it went up 42-48 but they were ok. Additional factors include the runflat frame, more steel than regulates tire behavior, lateral stiffness and better cooling. The PSI must also include spring rate, as well as vehicle weight, e.g. 400lbs extra.

When going 19" Michelin PSS4, all bets were off. Too low and the non-runflats become really mushy. Could not run 32 fronts. Then I analyzed the load, and car weight distribution, concluding that the front MUST run a min 34 PSI. Rear is different, cannot use the load as technically it could be 30. So suspension and the xDrive 60% rear traction also counts. When all was still uncertain, the chalk method really helped. Kid's chalk. chalk then take fast turns. That is when 32 confirmed wearing way to much on the tyre outside. So 33F/35-37R at 20C seems the best for me, with due consideration to them warming up. At 3-15C and 33F 35R is too high for 15-25C (expanding to 36F 39R) so must deflate.

1 to 1.5 PSI make a big, transformative difference in the handling of an M Performance xDrive at 3900 lbs. Too low and mushy, does not work with the suspension. Too high and rear risks disengaging or skidding. With my current DINAN Sways, Shockware and Spring setup, this is a real over-steer possibility if throttling it before hitting the apex.

My next step is to lower the rear, I maybe 33.5 - 34 all around despite the staggered, which explains the M3 M4 32 PSI all around set-up. But that car is 200 lbs lighter and uses wider tires. An M3 owner I know, whom drives his in Montreal 5-20C temps, wore badly the outside in just 10,000 kms (6,000 miles). Camber and PSI are meant to work when heated up, not cold temps. So Montreal cooler climate perhaps needs 34-35 PSI all around on the M3.