Uneven tyre wear - 95 300 TDi 110

Unusual one.....

Tyres on the front are wearing unevenly, drivers side has twice as much tread as the passenger side.

Tyres are same age (Grabber MTs), correctly inflated, and the same pressure etc.

Passenger side appears to be wearing significantly faster - none of the usual indicators of out of alignment, tracking, toe in/out, scubbing, or uneven wear from one side of the tyre to the other - just the quicker wear on the passenger side.

Any ideas anyone?

When was the last time it was machine checked. Or do you make more right hand turns than left, or alot of round abouts? time to rotate tyres