[kjx]

Temperatures are starting to fall off here and yesterday taking a corner hard I could feel the rubber band effect on the rear tires after the cornering ended and the rear "bounced" back.

This is always an indication for me that the tire pressure is too low causing sidewall flex and bounce back. And sure enough, it had fallen down to 34 psi. Now this is around what BMW recommends but I feel like they are pushing for a soft ride over handling.

My gut feel is that the fronts are fine/best at the recommended pressures but the rear is best run at around 38 psi.

What pressures do you run? Do you have similar thoughts on this? I run Michelin PS4S on 963Ms.

[jimbethesda]

I use the BMW recommended pressures.

[NightWriter]

Just make sure it's not 1.5psi too low

[Anderson11]

I use the BMW recommended pressures via the drivers side door sticker....

[Joachim]

kjx, this is (has been) my setup history, and the car didn't explode yet Seriously, I always had a safe driving experience with these setups:

May 2022 after driving home from dealer:

Front:
Michelin PS4S | 275/35 ZR19 (100Y) XL
2,7 bar (39 psi) at 37°C (98°F)
on 9.5J x 19 H2 [825M]

Rear:
Michelin PS4S | 285/30 ZR20 (99Y) XL
2,8 bar (40.6 psi) at 34°C (93°F)
on 10,5J x 20 H2 [825M]

No pressure correction made since then.

3 days ago:

Warning "check tire pressure" on the display at the dashboard:
4x 32 psi (recommended: 4x 36 psi) at 72°F

Now driving at 72°F
4x 37.7 psi | Recommended: 39 psi

NOTE: Temperatures as indicated in the car's menu, NOT environment temps!

[2011ninja]

Originally Posted by kjx

Temperatures are starting to fall off here and yesterday taking a corner hard I could feel the rubber band effect on the rear tires after the cornering ended and the rear "bounced" back.

This is always an indication for me that the tire pressure is too low causing sidewall flex and bounce back. And sure enough, it had fallen down to 34 psi. Now this is around what BMW recommends but I feel like they are pushing for a soft ride over handling.

My gut feel is that the fronts are fine/best at the recommended pressures but the rear is best run at around 38 psi.

What pressures do you run? Do you have similar thoughts on this? I run Michelin PS4S on 963Ms.

Connecticut

30 psi cold test; all 4 tire's; Pirelli zero

Temperature has dropped

Works for me

[evoi19]

During summer I run about 33/34psi measured when tires are cold. It gets up to about 36/37 when driving for some time.

During winter I increase to 35/36psi and it gets to about 38/39 when driving for a bit.

I'm on 4s also.

[davidmct-M3]

Originally Posted by evoi19

During summer I run about 33/34psi measured when tires are cold. It gets up to about 36/37 when driving for some time.

During winter I increase to 35/36psi and it gets to about 38/39 when driving for a bit.

I'm on 4s also.

Hi

Intrigued why you go up in pressure in cold. 32psi would be a different relative pressure depending on temperature as air density changes. I always inflate mine to 2.2 bar all round as per plate in car for whatever the temperature is outside.

Regards
David

[kjx]

If I'm counting right, we have 6 different preferences for 7 people. Lol.

[evoi19]

Originally Posted by davidmct-M3

Hi

Intrigued why you go up in pressure in cold. 32psi would be a different relative pressure depending on temperature as air density changes. I always inflate mine to 2.2 bar all round as per plate in car for whatever the temperature is outside.

Regards
David

I'm not an expert but I've noticed in my previous cars that in colder months my tire temperature isn't as high and my tire pressure doesn't increase as much. I should make a correctionto my previous post. During colder months, tire temps usually hover around 37psi. It rarely goes above 38 unless I'm driving for a long period of time. Also, in my area pot holes and cracks start to develop from the rain and the higher tire pressure helps with ride feel.

I pulled this from tire rack

https://m.tirerack.com/tires/tiretec...jsp?techid=168

Maybe I'm doing it wrong and open to suggestions but I was always taught this way.

[Purekoryo]

You guys run these too high imo.

PS4S run best at 33-34 psi HOT for best grip and steering feedback (I know it's almost non existent in our cars but it does make a noticeable difference to me).

[kjx]

Originally Posted by Purekoryo

You guys run these too high imo.

PS4S run best at 33-34 psi HOT for best grip and steering feedback (I know it's almost non existent in our cars but it does make a noticeable difference to me).

What's that measured cold? 30 psi?

34 psi cold in the front is good. Good steering feedback, soaks up bumps, etc. I don't really care about the front - it's very forgiving for a range of pressures. I don't take it down to 30-32 because that's lower than what BMW recommends in the car/app and what they recommend for the front works for me. Maybe I'll try it anyway.

34 psi at the rear is definitely not good for me because I can feel the squishy feedback at the back on rapid changes in direction near the limits where oversteer can start.

[Joachim]

Originally Posted by kjx

If I'm counting right, we have 6 different preferences for 7 people. Lol.

Hehe... It takes all sorts...

The basis for my individual pressure philosophy: here's my sticker:

[vetteflier]

32 in summer, as they heat up to 37-38 on highway. Just raised that to 34, as nights are much cooler now. You're always safe +2 psi. Not, however, -2 psi.

[2011ninja]

Originally Posted by vetteflier

32 in summer, as they heat up to 37-38 on highway. Just raised that to 34, as nights are much cooler now. You're always safe +2 psi. Not, however, -2 psi.

Just did same

Bumped my 30 psi to 32 psi

[buckybadger]

Originally Posted by kjx

Temperatures are starting to fall off here and yesterday taking a corner hard I could feel the rubber band effect on the rear tires after the cornering ended and the rear "bounced" back.

This is always an indication for me that the tire pressure is too low causing sidewall flex and bounce back. And sure enough, it had fallen down to 34 psi. Now this is around what BMW recommends but I feel like they are pushing for a soft ride over handling.

My gut feel is that the fronts are fine/best at the recommended pressures but the rear is best run at around 38 psi.

What pressures do you run? Do you have similar thoughts on this? I run Michelin PS4S on 963Ms.

Use the recommended tire pressure on your IDrive. I use it on my X5 and makes a big difference in ride quality.

[M3LISSA]

I'm like 33-34,35 in fronts and rears run like 35-36 but vary obv

[Tall Tom Cruise]

Here's an additional data point:

Cup 2's: 33 front, 35 rear
Southern California and 60-80 degrees all year

[jmg]

It depends on the tire, but generally what is recommended on the door jam is the COLD pressure. However, the overall better measurement is the HOT/OPERATING recommended pressure for your car's weight and driving style. That is determined by the wear on the sidewall. You can measure this by marking all 4 tires with chalk, going for a drive that represents the conditions you want optimal pressure for, then looking at how much of that chalk is getting rubbed off. Start low, and work your way up until you get minimal wear on the sidewall. Too much wear, and the pressure needs to go up. If you want to get super exact, measure the temperature across the tire contact patch and see if temps are too high on the edges (you can check camber this way too).

Of course, no one is going to do this on the street, it's unnecessary. This is what you do on the track to get the optimal pressure.


That being said, the "bounce back" you are experiencing is unlikely due to the tire pressure, and more to do with your dampening settings in relation to the road conditions. You are perhaps on sport + on the streets rather than just sport. Just stick with the cold pressures. You can also look up each tires optimal hot/operating pressures online and adjust when they are hot.

[madpistol]

35 front, 39 rear when warm.

[jmg]

Originally Posted by madpistol

35 front, 39 rear when warm.

39 is way too high for rears warm for me. Most of your heat is going to be front for cornering unless your doing donuts! 35 warm in back is the highest I would go for high performance driving on the *MPS4S.

[MT6]

Cold tire pressure I am at 36 psi Rears and 35 Fronts.

The drive on this set up for me is quiet stable on M3 G80 MT