265/35/19 PS4S ruined my CS

[CanAutM3]

Originally Posted by aboulfad

Coming from you that’s shocking, I expected some equations if it ain’t broke don’t fix it, it’s set to 32psi and ok. Once our climate warms up, I’ll experiment a bit.

Don't forget, I am a test engineer by profession (at least I was for a long time), so I do believe in empirical data .

[CanAutM3]

Originally Posted by aboulfad

Coming from you that’s shocking, I expected some equations if it ain’t broke don’t fix it, it’s set to 32psi and ok. Once our climate warms up, I’ll experiment a bit.

Note that the recommended pressures for my M4cs are 35psi front a rear.

I run 37 front and 35 rear.

[aboulfad]

Originally Posted by CanAutM3

Note that the recommended pressures for my M4cs are 35psi front a rear.

I run 37 front and 35 rear.

I recall seeing this config - higher front than rear: decrease understeer ?

[CanAutM3]

Originally Posted by aboulfad

I recall seeing this config - higher front than rear: decrease understeer ?

Nope. Optimize tire wear due to high camber on front axle .

I am far from the limit when driving on the street

[anurak]

Originally Posted by Billy_BMW

Try higher pressures, 45psi front and rear and see if there’s a difference.

OMG it works! I try today with Front: 38 psi Rear: 40 psi the car feels more direct and under WOT the rear doesn't feel wobbling anymore. Using the same road the oversteer in mid cornering is improved as well. It seems that PS4S side wall is much softer like you mention, using high pressure will fixed this problem.

[Steveo]

I’m getting slight rubbing on new PSS 295 30 20 on the rear on my M4CS, stock wheels.
Wasn’t expecting that to be honest with most comments saying 295s would be fine on the forum.
Stock suspension, no change in ride height.
Any ideas?

[CanAutM3]

Originally Posted by Steveo

I’m getting slight rubbing on new PSS 295 30 20 on the rear on my M4CS, stock wheels.
Wasn’t expecting that to be honest with most comments saying 295s would be fine on the forum.
Stock suspension, no change in ride height.
Any ideas?

Spacers?

[Steveo]

Did think about putting some on, maybe 5 or 7mm?

[RevNev]

Originally Posted by Steveo

I’m getting slight rubbing on new PSS 295 30 20 on the rear on my M4CS, stock wheels.
Wasn’t expecting that to be honest with most comments saying 295s would be fine on the forum.
Stock suspension, no change in ride height.
Any ideas?

295's are getting tall, but I wouldn't think they'd scrape at ET40. 285 Cup2's and Bridgestone S007A's don't scrape with 10mm spacers.

I couldn't get any 285 PS4S, nil stock in Australia and fitted Bridgestone S007A's on my 763M street wheels. My ZCP's in CS suspension spec with Eibach springs and the Bridgestone's have better lateral grip than the Cup2's on the street.

Cup2's need some heat that's hard to attain and maintain on the street and they're lousy when cold and I've found the Bridgestone's better to blast around a few favourite corners faster when the Cup2's weren't up to optimum temperature for maximum grip. The Bridgestone's don't throw as many rocks down the side of my car as the Cup2's and minimising stone chip potential's a bonus and they're quieter.

The Cup2's are better grip wise on a long spirited drive and I use them on my 19" track wheels, but as an overall street tyre, the Bridgestone's are pretty impressive and definitely don't degrade the car's transient handling on the street, quite the contrary. They're quite stiff in the sidewall where perhaps the PS4S aren't so much, but I can definitely say they didn't mess my car up on the street after familiarisation with Cup2's.

[RSXDC5]

God you guys complicate things. I’m glad everyone has discovered adjusting tire pressures changes tire dynamics. Please remember the 4S is a street tire, and not a pseudo race tire like ad08r/re71r which really needs a stiffer side wall. Usually, the more a tire tries to be a pseudo race tire, the stiffer it’s sidewall becomes (speaking generally).

Another thing people can do is step up their front rim width, then run the same 255 or 265 as before. It will be more stretched, less bulgy, and the sidewall will be less of an issue.

To the people using extremely high pressures on the 4S, how is your tread wear and how many miles do you have running the high PSI setup?

[Ropes]

21k so far and still several thousand more to go 😎

[JD1100]

Read through this thread and it seems there is no consensus on tire pressure. Seems more like a try and see type of thing.

Where do you guys think a good starting point is for cold tire pressure running 285-30-20 rear on a 10.5” rim and 265-35-19 front on a 9.5” rim ?

Tires are MP4S.

[ONEof500]

[JD1100]

Oneof500 thanks for the video link. Yes, I saw that a few weeks ago. Seems like generally the 4S is better than the super sport.

Was still wondering about the tire pressures .