[Ikester19]

Originally Posted by Chris DW

I'm not really sure if the recommended tire pressure @ 38 psi on my G20 m sports is even correct if it's on solo drive daily. I've recently check my rear tire tread depth and the signs tells me that it's over inflated... I'm getting centre wear. Have decided to drop my rear positions to 33 psi and reduce the fronts to 35 psi. The car in on 19" and has only done 11,000 kms .

That seems to be the opposite story to mine, I run front and rear at 40psi and tyre wear now seems even. Previously ran all four corners at 38psi and found the outer area of the tyres wearing prematurely.

[alpinewhite3]

Originally Posted by Chris DW

I’m not really sure if the recommended tire pressure @ 38 psi on my G20 m sports is even correct if it’s on solo drive daily. I’ve recently check my rear tire tread depth and the signs tells me that it’s over inflated... I’m getting centre wear. Have decided to drop my rear positions to 33 psi and reduce the fronts to 35 psi. The car in on 19” and has only done 11,000 kms .

Also a solo driver and similar experience with 38psi. Just swapped tires and found the the outer edges to have a tiny bit more tread left. Fronts at 32psi look about even.

Im guessing the recommended pressure accounts for a possible maximum load (safety reasons)

I now run 34-35 front 36-37 rear.

[MBM340]

Originally Posted by alpinewhite3

Is your car x-drive or RWD? i have been doing extensive research on tire pressure and trying out different pressures to maximize steering feel/grip/ etc.

I have RWD, what have you found with different pressures with that setup? I have usually kept mine both front and rear at about 34 in other RWD cars, but have not experimented in this one...
Thoughts?

[alpinewhite3]

Originally Posted by MBM340

I have RWD, what have you found with different pressures with that setup? I have usually kept mine both front and rear at about 34 in other RWD cars, but have not experimented in this one...
Thoughts?

Couple of main takeaways -

Never run above 40psi in any 18-19 inch performance tire. The ideal grip "band" is between 32-38psi for most performance tires. If you go beyond 40psi, you may end up with a tire that feels better since you are greatly enhancing steering response at the expense of overall grip.

BMW recommends 32F 38R on their RWD 330i b/c their #1 goal is safety (from a liability perspective). My best guess is they recommend 38 on the rear b/c a higher pressure in the rear will prevent the sidewall from flexing too much and greatly prevent the car from oversteering. 32 on the front will keep it squarely planted at the limited with max grip available. I'm sure the toe/camber settings are calibrated to prevent oversteer too.

I like to run 34-35 front 36-37 rear. 2 PSI difference.

I found the 32 front made the steering a bit too dull. 38 Front is super sharp but i can feel the lack of grip. 34-35 is a happy medium.

38 rear is too high (a tiny bit too much center tire wear) so i run 36-37.

[MBM340]

Originally Posted by alpinewhite3

Couple of main takeaways -

Never run above 40psi in any 18-19 inch performance tire. The ideal grip "band" is between 32-38psi for most performance tires. If you go beyond 40psi, you may end up with a tire that feels better since you are greatly enhancing steering response at the expense of overall grip.

BMW recommends 32F 38R on their RWD 330i b/c their #1 goal is safety (from a liability perspective). My best guess is they recommend 38 on the rear b/c a higher pressure in the rear will prevent the sidewall from flexing too much and greatly prevent the car from oversteering. 32 on the front will keep it squarely planted at the limited with max grip available. I'm sure the toe/camber settings are calibrated to prevent oversteer too.

I like to run 34-35 front 36-37 rear. 2 PSI difference.

I found the 32 front made the steering a bit too dull. 38 Front is super sharp but i can feel the lack of grip. 34-35 is a happy medium.

38 rear is too high (a tiny bit too much center tire wear) so i run 36-37.

Agree fully they want to prevent oversteer. All manufacturers want the cars they sell to the masses to understeer at breakaway because that is MUCH easier to control by slowing which is what 99 percent of people do just due to natural reaction which then allows them to control the car again.
Interesting on the recommended 38 rear though on the 330. Also agree they want to the car firmly planted but wow, 6psi difference is a lot if you ask me.

Once Spring comes I will try some different psi's and let you know. Thanks for the info.

[spb]

Need some help. Just installed new tires and computer says low pressure.

Sticker recommended:
32 front
38 rear

Computer recommended:
34 front
42 rear

I manually reentered tire size and still same numbers. Why different numbers btwn computer and sticker?

[GusL]

Originally Posted by spb

Need some help. Just installed new tires and computer says low pressure.

Sticker recommended:
32 front
38 rear

Computer recommended:
34 front
42 rear

I manually reentered tire size and still same numbers. Why different numbers btwn computer and sticker?

I believe the on board computer also accounts for temperature, usually the sticker pressures are based on 15-20°C. Is it particularly warm where you are? What tyre temps is your car reading?

[spb]

The outside temperature is 14°C (57F).

[GusL]

Originally Posted by spb

The outside temperature is 14°C (57F).

What sizes are you running please?

[Bc2005]

My M340i has Pirelli P7 run-flats with stock 225/40R19 square setup and the onboard monitor recommends 38/41 psi. It’s good for the highway, but the run-flat P7’s can really be jarring on low speed bumps or washboard roads when you have the sport suspension. I don’t really like the ride of these tires. I don’t have enough miles on it yet to assess how they are wearing.

When they swap tires on your car they should either read the QR code on the tire and use it to update the car’s computer, or they should manually enter the tire data. After that update the onboard system might recommend a different pressure than the pressures on your OEM sticker. AFAIK they never change the stickers.

[G30M]

have PZ4 RFT 19" staggered and going on a road trip with 2 proper teens and their stuff in a wagon

setting pressure at 36 front 39 rear

i am so confused since my subaru recommends 32 psi and the BMW door says 39/39 with 3 bodies and 44/49 with 5 bodies