Uneven tyre wear on front tyres - do I have a big problem?

[Logan]

Had a look at my Z4MC tyre wear today. I am in need of rear tyres quick as down to 1.6mm ribs. I am going to go for the Michelin Super Sports in 265/40/18s. My front tyres have about 1000 to 1500 miles left on them and then they will get changed to 225/45/18 Michelin Super Sports.
This is the issue - the tyre wear is on the outside shoulder on the front left tyre and the inside shoulder of the front right tyre.
What could this be due to?
Track day (previous owner) perhaps going clockwise all day?
Wheel tracking?
Bent suspension?
The car doesn't pull to either side when driving or when braking.
Any thoughts out there?
As a second issue - does changing from the OEM tyre size do anything with the traction control (or any other electronic wizzerdry the car has)as the front and rear wheels will then be going at slightly different revs then the OEM set up - or is the 1.2% circumference difference too small to affect it. My thoughts on this were it shouldn't make a difference as you can get a bigger difference if fronts are new with 8mm tread and rears are worn with 2m tread.
Now I'm typing this I've thought of a 3rd issue - what tyre pressure to run these slightly oversize rears at?

 

[mmm-five]

Can't help with the wear problem, but I'd recommend you get a decent alignment done once you've got your new tyres on.

I've done a few track days & 'ring trips in mine, plus almost 50,000 road miles, and my annual alignments show almost no change year to year, although any slight change is dialled back out.

I've also not experienced any odd tyre wear on the front, and only get the regular half bald/half fine effect on the rears.

I don't particularly find my driving style induces much understeer either, so haven't been tempted to dial in any extra front negative camber.

I've also kept the tyre pressures to the same as standard, but the Motorsport-derived, square sidewall/shoulder will make the tyres feel a little stiffer, which of course helps with the feel and quick response.

 

[daz05]

You can get a free alignment check done, do that and then see if there are any issues.

 

[pilchardthecat]

Every BMW i've ever (5 of them) had worn the front tyres on the outer edge. This is before/after full BMW alignments. It's normal/my driving.

Inner wear is not normal! Dodgy camber i suspect



(ps - sounds daft but are the tyres directional, and are they on the right way.....)

 

[Logan]

Thanks for your comments. I've gone ahead with my purchase and am now running on Michelin Super Sports. 225/45/18 front, 265/40/18 rear. I'm currently running with 32 psi front and 34 psi rear.
I had the tracking checked and it was spot on - so I don't know what the uneven front tyre wear was all about. I have bought a tyre tread depth gauge, and intend to keep an eye on how they are wearing.
Now as it is such a lovely day, I ought to get back out into my car and put a few miles on those tyres.