[22M340iAZ]

I used to take my m3 xdrive on high speed runs a lot, over 130+ and the car has always felt planted. I changed my pzeros to PS4s and it feels terrible, the back feels delayed to the front and at high speeds there is no control over the car, no vibrations just the car swaying from left and right. This is the same thing that happend to my x6m and I can’t figure it out, it’s been more than 500 miles to the new wax is definitely off, I hate it and I can’t figure it out. Tires were heated up aswell, had an m340i before this and had same tires, no problems at all. What is going on, why only on the m’s this happens

[Schulminator]

Your pressures, especially in the rear is high. I'd try 35ish cold all around and see if it helps.

[SwankPeRFection]

Pressure are too high, especially in the back if you say you feel the back sway too much. Anything at 40 or past it will feel like that and even more so on the bs soft sidewalls of the Michelins. Lower to 36 or 38 and see how it feels.

[22M340iAZ]

Originally Posted by Schulminator

Your pressures, especially in the rear is high. I'd try 35ish cold all around and see if it helps.

Originally Posted by SwankPeRFection

Pressure are too high, especially in the back if you say you feel the back sway too much. Anything at 40 or past it will feel like that and even more so on the bs soft sidewalls of the Michelins. Lower to 36 or 38 and see how it feels.

Okay I will lower it, I put it to what bmw said to put it at so I will try yours and will lyk, thank you guys for the quick responses

[GolfCoyote]

Swaying? You might be "tramlining" a bit. Stickier or wider tires can do this. Alignment might be out of whack too. And like others stated, PSI (especially in the rear) is a bit high and will only get higher the faster you go.

[Bimmerfun82]

Originally Posted by 22M340iAZ

Okay I will lower it, I put it to what bmw said to put it at so I will try yours and will lyk, thank you guys for the quick responses

What did BMW recommend for the cold tire pressure? Did you go with the door jam or the manual?

I was reading the CS track day front page and at the track the PS4S was seeing huge jumps in tire pressure.

[22M340iAZ]

Originally Posted by Bimmerfun82

What did BMW recommend for the cold tire pressure? Did you go with the door jam or the manual?

I was reading the CS track day front page and at the track the PS4S was seeing huge jumps in tire pressure.

I went with what it said on screen to do when it gave me error it said inflate to 45 in the rear

[Bimmerfun82]

Originally Posted by 22M340iAZ

I went with what it said on screen to do when it gave me error it said inflate to 45 in the rear

Weird. Door jam says 32/33. Mine heat up to 38 which should be good for high speeds.

[22M340iAZ]

Originally Posted by Bimmerfun82

Weird. Door jam says 32/33. Mine heat up to 38 which should be good for high speeds.

Seems much better at the lower psi, still haven’t raised speed to over 100 but feels way better already thank you guys

[Skyscraper]

Originally Posted by 22M340iAZ

I went with what it said on screen to do when it gave me error it said inflate to 45 in the rear

I recently had the same problem. Tires were set to 33psi and the info kept telling me pressures were too low to raise to 44 or 45.

See if your tire setting is set to winter tires. Change it to summer and run the reset.
If that doesn't work have the dealer check it next time you're in for service.

[RUNSOK]

Running high pressures reduces your contact patch and makes the car feel more nervous. Bleed it down it will settle down

[22M340iAZ]

Originally Posted by Skyscraper

I recently had the same problem. Tires were set to 33psi and the info kept telling me pressures were too low to raise to 44 or 45.

See if your tire setting is set to winter tires. Change it to summer and run the reset.
If that doesn't work have the dealer check it next time you're in for service.

Ye it’s weird but do you have to have the settings correct on the car or can I just set it to whatever doesn’t give me an error

[BimmerFix]

Originally Posted by 22M340iAZ

Ye it’s weird but do you have to have the settings correct on the car or can I just set it to whatever doesn’t give me an error

Just set it to 33-34 cold , you won't get any warnings . Problem solved
& no more swaying issues moving forward

Rn your front end grip is considerably higher than your rear . Hence the floaty feeling at triple digit speeds

[edi221]

I like to add that you can change the setting for the tires, at the tire pressure settings, they are asking if you are driving summer tires, and even the sizes, this will affect the settings for the tire pressure.

Hope this helps.

[BackOnBlack]

Besides the pressures, if the tires are brand new, they need to scrubbed off a little first, so the initial 200-300 miles won't be optimal.

Also, check your alignment, specifically the toe settings. Mine were really off from factory, and that would create instability at high speeds.