Michelin Pilot Sport 4 S on an M

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hopz121
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Michelin Pilot Sport 4 S on an M

Post by hopz121 » Tue Aug 29, 2017 5:08 pm

Try 34 Front 36 Rear OP

And add a bit more until it feels better or worse.

It could be the fact you have gone to the 19's too to be honest it will most likely drive better on the 18's and it maybe a little more crashy hence the TV light.

Try the pressures and add a few more miles on and see what happens
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Michelin Pilot Sport 4 S on an M

Post by samZ4M » Tue Aug 29, 2017 5:10 pm

Yea, they'll get upped tonight and tested.

It really is as bad as 3rd gear, 3k RPM and the light is coming on. I will turn traction off and see if it actually breaks (traction) or not. I don't think it's actually doing so though. I don't feel the power get cut, even in a corner.

I barely could get the light on with the 18"'s and MPSS', with some serious abuse coming out of corners, even nailing it in 2nd, nothing.

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Michelin Pilot Sport 4 S on an M

Post by MACK » Tue Aug 29, 2017 7:38 pm

As general rule when you loose either some tyre width or height your going to need more air pressure to support the vehicle to the same extent. I'd try keeping the 2psi difference between the front and rear and going up in two psi increments till your 6 or 8 psi above where you started. If that doesn't sort it, or if it makes it worse then its a fair bet your barking up the wrong tree or tyre pressure isn't your only issue here. With what your saying about breaking traction in corners the alignment could be out or something on the suspension could well be knackered and only showing up due to the extra weight f thee new wheel/tyres.
Did you ever manage to get the alignment check? I would also find out the weights of your new wheels compared to your old ones, those coupled to the extra weight of the bigger tyres could well be your culprit but I suspect its actually a combination of factors here.
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Michelin Pilot Sport 4 S on an M

Post by samZ4M » Tue Aug 29, 2017 7:44 pm

MACK wrote:
Tue Aug 29, 2017 7:38 pm
As general rule when you loose either some tyre width or height your going to need more air pressure to support the vehicle to the same extent. I'd try keeping the 2psi difference between the front and rear and going up in two psi increments till your 6 or 8 psi above where you started. If that doesn't sort it, or if it makes it worse then its a fair bet your barking up the wrong tree or tyre pressure isn't your only issue here. With what your saying about breaking traction in corners the alignment could be out or something on the suspension could well be knackered and only showing up due to the extra weight f thee new wheel/tyres.
Did you ever manage to get the alignment check? I would also find out the weights of your new wheels compared to your old ones, those coupled to the extra weight of the bigger tyres could well be your culprit but I suspect its actually a combination of factors here.
Yea, the 2psi increase is what I was doing, I forgot over the weekend to up them. Currently on 33/36 I think.

It's just passed an MOT with new springs on the rear, which is an other factor!!

I run CSL reps with Sport 4 S', so good rubber! Loads of people run those wheels, so I can't see that the problem. I'll do pressures over the next few days, and get an alignment done this weekend.

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Michelin Pilot Sport 4 S on an M

Post by MrPT » Tue Aug 29, 2017 9:02 pm

hopz121 wrote:
Tue Aug 29, 2017 5:08 pm
It could be the fact you have gone to the 19's too to be honest it will most likely drive better on the 18's and it maybe a little more crashy hence the TV light.
I reckon it might just be this too. It's a compromise - you are losing 4cm of squishy stuff per corner vs stock (assuming CSL tyre sizes), and the rear axle is skittish enough as it is, even with the 18s. Try and find a supercar with skinnier rear tyres than an M3 CSL. It's hard!

TC light on at 3k in 3rd is odd though. Worth more experimentation. Are you sticking with stock geo or reducing the rear camber?
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Michelin Pilot Sport 4 S on an M

Post by samZ4M » Tue Aug 29, 2017 10:18 pm

Geo was done as stock 10,000 miles ago with the last set of rears (18" though)

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Michelin Pilot Sport 4 S on an M

Post by samZ4M » Sat Sep 02, 2017 2:18 pm

Geo was a fair bit out (only done a year ago). Added a fair bit of rear camber, he reckons the tyres were skimming the inside of the arch too.

Seems better already, but not done that much mileage. Will let it cool and check pressures and go for a run, any excuse!

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Michelin Pilot Sport 4 S on an M

Post by dgm » Sat Sep 02, 2017 4:50 pm

I've run 19" Michelins on my car for a good few years, IMO the optimum tyre pressures are 33 rear, 32 front. The car drives very well on 19s and I've never recognised the opinions that say the 19s wreck the ride. The cars originally came on 18" Contis which were by far the worst performance tyre I've ever encountered, Michelin PS2s provided a far better ride and improved handling. The technology has moved on leaps and bounds since PS2s as well. My point? The tyres size increase from 18s to 19s is very unlikely to be causing your problems. As said, you need to be looking at your suspension. I'd also check that the replacement springs that were fitted are the correct spec.
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Michelin Pilot Sport 4 S on an M

Post by samZ4M » Sat Sep 02, 2017 9:07 pm

The guy who done the alignment was thorough and said bushes seemed ok, but would benefit replacing as it's knocking 75k. If it were bushes, I'd have noticed it more on the last wheels/tyres too. All of them don't just go at once.

A evening jolly and I can confirm it does feel better, but the light still comes on in certain circumstances, even in 3rd. The power is not cut though, so is it just braking the corners? I'll redo the tyres when cold tomorrow, but they should currently be 33/36.

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Michelin Pilot Sport 4 S on an M

Post by MrPT » Sun Sep 03, 2017 12:42 pm

samZ4M wrote:
Sat Sep 02, 2017 2:18 pm
Geo was a fair bit out (only done a year ago).
Doesn't look to bad apart from that RL toe. Think a lot of people would be happy to go down to 1.2deg rear camber.
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