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      03-20-2018, 08:32 AM   #8
gIzzE
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Drives: F11 + 911 C4
Join Date: Apr 2006
Location: Norfolk, UK.

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Quote:
Originally Posted by LazyHound View Post
For normal everyday driving, mixing RF and normals front and rear is perfectly fine. Only issue is when running them on same axle - you won't feel any difference. Ideally replace all at same time but life gets in the way, aslong as there legal all is good.

I did it years ago on my 118d, put the RF on rear as they were just too hard, soon wore out after few 10k, then swapped all.

Sorry completely disagree.

Not saying you couldn't put a Michilen Pilot Sport run flat and a Michelin Pilot Sport non run flat on the car, the fact they are run flat and normal isn't the issue.

The issue is different tread patterns.

As you move up in power you will notice more of a difference, however, if you know what the signs are you will notice it with any BMW.

The way to test how much it can throw out a BMW is as you come off a roundabout that is damp give a little extra gas, not silly amounts, just a bit more and you will often feel the back end twitch out and the traction light come on. It shouldn't do this, in fact it is pretty hard to get it to do this with 4 matching tyres.

I am amazed at how many BMWs I see used have different tyres front and rear.

I never knew about it until I had my M3 CSL.
It was a twitchy mess, BMW replaced dampers, springs, then all the control arms and bushes and it was still not right. Problem was no one there really knew if the CSL was just like that.
I then got a call one day to say a tech from another main dealer was covering at Norwich for the week, he raced CSLs and they said to come over and he would take mine out.
We took it down the slip road onto the dual and then took the first exit off, as soon as we hit that roundabout he said "You have different tyres front and rear!"
I was adamant I had Pilot Sports all round.
We pulled over got out and sure enough PS on the front and PS2s on the rear.
We went back, put PS2s on the front and the car was transformed.

Now, going back down to something like a 320d you don't notice it in the same way, but when I did it for a few days you could tell it was doing what the M3 was doing just less aggressively.

I guess the point is, we tend to buy BMWs as we like to push on a bit, we enjoy driving, mixing tyres takes away a lot of the balance that a BMW gives you.


Now, having said all that, you can get lucky, I bought some 18" wheels for track and I had ordered some Pilot Sport 2s for them, when they arrived they had Kumho's on them. The tyre shop put on the PS2 rears and then realised the fronts were the wrong size. I ran round with them on for the best part of a week, and to be honest they were fine.
But looking at the tyres the tread was almost identical, which I think makes a the biggest difference.



When I say budget, I mean Kumho etc. not sime rock hard Chinese ditch finder.
I would prefer 4 Kumho or Vredesteins over a symmetrical tyre front and asymmetrical rear even from the same brand.

This has been discussed ad nauseam on BMW forums over the years.
Deniers deny until they experience the it, or rather they notice more how much more grippy the car is on 4 matching tyres.

Last edited by gIzzE; 03-20-2018 at 08:45 AM..
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