The cause of inner edge tyre wear is excessive toe out, maybe these tyres are more affected by it for some reason.

Could this be 'rubber' suspension mounts that have softened with age and are allowing the alignment to be pulled out whilst power's applied under normal cruise conditions?

Fair point Tom, many cars suffer quite quick suspension wear, hardly surprising the state of the third world urban roads, road calming assault courses etc.

OP you can get a fair feel for suspension wear without jacking the car up, gripping the wheels well try to move the car forwards and backwards by attempting to rotate the wheels, surprising the amount of movement you can get if things are worn.

Obviously you'll try the more usual wheel movements in other plane's as if testing for worn ball joints too.

It's not surprising that the front wheels feather, even my perfectly aligned RWD MB wears all 4 shoulders down too soon but evenly, though my driving is more than partly responsible, not sure why your rears should be the same mind.

edit, ah it's a SWMBO's car...is she a secret girl racer once out of sight..:-)

Edited by gordonbennet on 29/09/2011 at 13:01