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I doubt your tyres are faulty. What might be an issue is enough of a difference in the rolling radius between the two tyre models front to rear. The traction control on your open diff will brake the wheel it thinks is slipping to aid traction. This in turn would cause wayward handling even in a straight line under acceleration.
 

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Discussion Starter #22
Given you know you had issues mixing PS4 rear and MPSS front surely it is reasonable to think PS5 rears and PS4 front may be an issue.

I had similar on my M135 with F1 assy 4 rear MPSS front a while back and more recently when I had to put F1 assy 5 rear to assy 4 front.

It wasn't as bad as your description. I would describe it as "disconnected". The fronts have since been replaced and all is well.

It's a PITA. I always try and match exactly but given the constant changing of tyre ranges it is often not possible.
The other tyres (e.g. PS4/MPSS mix) used different designs, compounds, tread pattern etc - so because the PS4 and PS5 are pretty much identical, including the tread pattern I thought it would be OK.

I can live with it, but its certainly an odd feeling - did an overtake yesterday at higher speeds on an NSL road and I had to hold on to it quite a lot!!

It's annoying with BMWs that the fronts last twice as long as the rears and can't be switched F to R, as you always end up with that overlap, which with my miles is every 2 years.
 

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Discussion Starter #23
Any heat from wheels? Take it for a blast and see if you can feel any heat from the discs.
What you're describing is what I had after I had my PS5's fitted. Purely coincidental mind.
I had sticking caliper, at speed 60mph+ a fair bit of wobble at speed and dragging which was due to the rear left brake not disengaging.
Replaced calipers and back to normal.
No, callipers are fine, no issues with braking.

Certainly some traction issues though, as even in the current hot/dry weather I'm getting some bogging down, and minor slip when applying throttle - all on roads where the PS4 would have never even slipped.
 

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The traction control on your open diff will brake the wheel it thinks is slipping to aid traction. This in turn would cause wayward handling even in a straight line under acceleration.
Yep, the bit about the traction light coming on when its going in a roughly straight line makes me think this too, Ive had the same issue on a 3550Z running wildly different sizes from standard
 

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It certainly sounds similar to an issue guys were having with the 255/30/19 front and 235/35/19 rear set up on the 8V RS3’s when fitting MPS4S. The traction control would cut in even on light throttle. When they fitted 235/235 all round it fixed it. No one knows the exact issue but it sort of seemed like it could be down to a big enough difference in rolling radius making the TC overly invasive.
 

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Discussion Starter #26
It’s on completely stock tyre sizes though, so there isn’t any difference in rolling radius, or in the tread pattern either. If you view the ps5 and ps4 from above they’re identical. 🤷
 

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Discussion Starter #27
Also, both things are independent. So the tc is only flashing on proper full beans and with slight steering input, but not always. The funny handling/swaying is just when going over 50mph with higher pressures - whether flat out or not.
 

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I had a issue with Michelin PS4S on my M4. Anything above 50 started wth serious vibration on the wheel as feedback. When my local tyre fitter put the front right wheel on the balancer we noticed the slightest bump in the tyre as it was spinning. Tyres had only about 50miles on them so Michelin are replacing the faulty one FOC.
 

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There's always going to be a question mark re problems if all four tyres aren't the same. There are likely to be significant build and compound differences between the two different tyres you have, even if they're from the same family. A typical quality performance tyre has around 600 components, so ther's a lot of leeway for these to change from one version to the next i.e. from PS4 to PS5. I'm afraid that until you standardise all four, it's going to be hard to diagnose. And ideally, they will also be new, or certainly no less than 4mm tread.

Yes, tyres can be faulty as a result of manufacture due to dodgy compound mixing, poor machine setup, a bad batch of components etc. although it's fairly unusual. One thing that might be worth cheking is the inside of the carcass: there's always a possibility that there's a visible internal fault (like bubbles, which arise for a number of reasons) that'll be really obvious and will clearly point to the root cause. Taking them off, examining them for problems, then replacing them also gives the opportunity to re-balance everything and check for distortions like that mentioned by @Rabbbieburns as well.
 

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Long post alert!!

I've had plenty of tyre issues on my 240 since buying. When I changed the rears from stock MPSS to PS4 the car was dangerous, as per the thread I made about it. It was weaving around at the back over 50mph and it was difficult to control the car.

So I bit the bullet and ditched the front MPSS with 4mm of tread left and put some more PS4 on. This fixed the issue thank god. The car was then perfect for 11k miles on the PS4 - a joy to drive, very very quick off the line wet or dry and even with just 2mm tread left on the rears the grip was unreal.

However, those rear PS4 wore out recently so I had brand new PS5 fitted instead of PS4. So I currently have new PS5 R and 18 month old PS4 front with 4-5mm tread.

And once again I've had nothing but issues. On the motorway, going over 50mph it was again swaying badly so I thought the pressure may be wrong - they were all over thanks to ATS so I put them to my usual 32F/36R setting and tested them - it was still not right. :(

So I tried more in the rears and put it to 34F and 40R PSI and it was unbelievably dangerous - the car was literally moving at the rear as if it had 4WS and as I hit 50 it was swaying around - I honestly thought it was going to spin!! o_O:cry:

So I tried lowering it all round and put it down to 30psi on all 4. This has cured some of the issues, it no longer sways around over 50mph but I've noticed other problems.

It doesn't have that mega bite from a dry start that it used to have - even in Sport+ if I give it full beans it feels like its bogging down a lot. But not all the time, sometimes its blistering, other times it feels like the torque is being throttled - the PS4 never did this!!!

But worse of all, if I'm in Sport and giving it absolute full chat, say going up a motorway slip road and onto the motorway, any slight steering angle and the traction light is constantly flickering - not just a bit, but constant and it carries on even when I've lifted off and am slowing down. I just had a blast then and with very slight steering angle at something just over 70mph ( :whistle:;) ) it was spongy at the rear and I could see the TC light flashing again, this is in 6th or 7th gear flat out (no cars around).

I honestly don't know what's happened. I've lost confidence in the car now and it feels much worse to drive. But in the current climate I can't really chuck £300 at another front set of tyres.

So, can tyres be faulty and is it worth contacting Michelin to look into it? It's really annoying me now and putting me off driving the thing. I don't really want ATS messing with it again, they buggered up my wheels as it was.

Or is there anything else it could be, wheel sensor, tpms or something else.
Dude it's your traction control struggling to calculate what's going on because you're mixing worn tyres on the front with full tread tyres on the back. This creates too large a variance in the diameter for the computer to deal with. This is a known issue for this car and using old and new tyres together should be avoided! In fact you answered this yourself when you said you had the same issue with the new PS4 on the rear and old MPSS, but when you replaced the front the issue resolved. You've done exactly the same thing again with the PS5.
 

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Discussion Starter #31
Dude it's your traction control struggling to calculate what's going on because you're mixing worn tyres on the front with full tread tyres on the back. This creates too large a variance in the diameter for the computer to deal with. This is a known issue for this car and using old and new tyres together should be avoided! In fact you answered this yourself when you said you had the same issue with the new PS4 on the rear and old MPSS, but when you replaced the front the issue resolved. You've done exactly the same thing again with the PS5.
But what is the answer to this?

The rear tyres are done after 2 years/11k miles but the fronts last much longer - easily 4 years and 20k miles at least.

I can't throw away perfectly good tyres every 2 years that have 4-5mm of tread left to balance this issue. Oddly, we don't have these problems on our E91 which gets new rears every 2 years and new fronts every 4. My old E81 also didn't have the same issue either and that had different brands F to R!!

So it's either something specific to the F22 cars or it's something else.

And the PS4 and MPSS are vastly different tyres which explains those issues, the PS4 and PS5 are supposed to be very similar according to Michelin.

Surely in current times, with huge financial pressure you guys aren't just chucking away £300 worth of front tyres every 2 years?

Also, just to point out, this seems a very specific issue that's only on the motorway at higher speeds. Using the car as intended round the back roads up to 60mph+ the handling and TC is absolutely fine. I have no issues other than stability on the motorway.
 

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I think some cars are sensitive to tyres more than others. I fitted Uniroyal rainsport 5 to my 1 series and got very similar handling issues to yours. I am wondering whether it was down to the fact they tres have quite soft sidewalls. Is the PS-5 more comfort orintated compared the PS-4?
 

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Discussion Starter #33
I think some cars are sensitive to tyres more than others. I fitted Uniroyal rainsport 5 to my 1 series and got very similar handling issues to yours. I am wondering whether it was down to the fact they tres have quite soft sidewalls. Is the PS-5 more comfort orintated compared the PS-4?
No, it's a direct replacement UHP tyre, so it's replacing the PS4 and they will have the PS5-S soon as well. I know a lot of the M3 lads are running the PS5 now as well.

It must just be slight differences between the tyres, as msej449 says as with PS4 all round the car was spot on.

I'm just having to get used to it now, although with Tesco99 approaching £10/gallon now I may not keep the car for much longer the way things are going!! :ROFLMAO:
 

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Hi are they star marked tyres ? dont have to be runflat but OEM for the car as lots of tyres are graded hence why some distributers can sell them alot cheaper ! BMW ones from new are A grade , the cheaper the tyre place the lower the grade might be worth asking if they are BMW specific ? Porsche and Mercedes also run specific tyres OEM as when I fitted Michelin Ps4 to the Porsche they had to be N rated .
 
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