Original spec rear tyres (pilot sports) changed for Gyear GSD3. Ever since have trouble keeping car on the road, squirms all over the place traction control permanantly lit up. hi speed motorway driving feels unstable.

Manual says tyre pressure should be 42, and tyres are at 42 when cold. Anyone else had a similar problem?. BMW reckon tyre issue.

Could it be they are directional or assymetrical tyres that are on the wrong way round? Easy mistake to occur.

For Directionals: Check the sidewalls on the all tyres for the direction arrow, and make sure the arrow points in the correct directions for forward motion.

For Assymetricals: make sure that the tyre wall on all the tyres has "Outside" stamped on them, if they are backwards you will find "Inside" instead.

I only say this, as when I had my XR3 serviced many years ago before my scoob, some goon put the wheels on the the wrong way (directionals). Being unable to stop in the wet made me notice something was up! :eek:

could be that the fact that the rear tyres are larger than the fronts (due to being a different make and new) and causing the traction control to think that somthing is up.

[Edited by mikelmr - 9/14/2003 4:55:19 PM]

Swap front to back, not forgetting to readjust pressures, and see if it makes any difference.

Traction control light on permanently ? Sounds like it's faulty?, possibly meaning it is applying one of the brakes as well ? which could explain it.

Surely the dealer could swap your wheels with some others to verify, and they should also be able to diagnose the fault on the DSC easily by plugging it into the computer.

[Edited by russell hayward - 9/14/2003 6:49:16 PM]

check widths before swapping front to back - BM's have diff width
front and back (on v6's anyway) my 328 has 225/245 front back.

new tyres have a greasy film when new, which wears off after a few miles...maybe there is some greasy on the treads?

take it back to the fitters i say. if the car is physically skirming, then the ASC light will come on - i.e not faulty

Thanks guys, this is a friend's car - The tyres are on the right way round, and as woz says, unable to swap as rears are 255, fronts 225.

Went out in it yesterday and it seems to be slight understeer cauing the problem, so have suggested putting a couple of new F1's on the front to match. It's in with BMW for them to check it out today anyway.

F1's have quite a soft side wall which would account for the "sqirmyness" your mates feeling. Try increasing the pressure in the rears by a psi or two, see if that tightens things up.

Matt,

Have heard of this happening on several 3 series. Tends to be when tyres of different makes are used. I used to think that if you had the same tyre on the same axle, that it was Ok. Apparently not. If he changed teh fronts for the same make of tyre, the problem should go away.

The strength of the sidewall may also be an issue. I use the Bridgstone RE040 on my 330d Sport, as it's the tyre the car came with. They're standard fit on GTR34 Skylines, so they're OK, if a little hard. ;) The sidewall is very stiff, and I've never had "squirm" issues.

Cheers
Matt

[Edited by MattOz - 9/16/2003 9:39:50 AM]

Bridgestones are std on the 325 sport for a 52 plate.

They are a straight 6 engine, not V6 too!

BMW have told him its tyre related. Thanks for your input guys.

The car has mich pilot sport as standard but they are incredibley expensive in those sizes.

He's just got to buy two more tyres now;)

had the same problem with my 325i when i put new F1's on the rear.
changed the fronts to F1's and it was great!

I'm about to put F1s on the back of my Z3M. They'll be ok won't they?

best tyres iv ever had. so much control.