I seem to be getting weird tyre wear on my A4. The front left tyre has worn more (across the whole tyre - maybe a touch more on the outside) than the front right. The front right has about 6mm left the front left has about 4mm left. The front right had a leaking valve but I got this fixed 2-3 weeks ago and it's been fine since. Tyre pressures are at 33 psi all round. The car is on oem SE suspension (covered 92k), the original 16" wheels and Michelin Primacy HP tyres all round. All 4 tyres were fitted at the same time. Any pointers to what could be causing this or is it nothing to worry about?