CAUSE OF INNER EDGE WEAR
This may be of relavence:
Many yuears ago I owned an Escort Cossie for my sins. Bought it new, and from about 5k miles it started an apopetite for front tyres which meant a pair of fronts would last only 2-4000 miles.
If you read Performance Car back then, when Clarkson was a humble journo, you will know he had one of these cars, and exactly the same issue.
The front suspension on the cossie uses a strut, the bottom of which is held in position laterally by a single lower link to the chassis, and by the front ARB longitundially.
During one tyre change, the mechanic and I noticed that upon torquing the wheelnuts, the wheel would move slightly fore and aft in the wheelarch.
The Escort Cosworth used front suspension derived from thye 60bhp 1.3L Sierra. The cause of the issue was found to be a geometry change which would only occur dynamically under braking, which led to the geometry moving from parallel to a massive amount of toe out whenever you braked, thus scrubbing the inner edges of the tyres to death.
To reiterate, on a standard static geo check the problem did not show up.
Now I'm not sure of the design of the 159 front suspension, (I am on this forum to debate the buying decision of a 159 or a GT - both diesel.) but I think this is well worth looking at.
I would suggest a 2 foot breaker bar on a front wheel nut, handbrake on, and put the tightening torque on the bar. Check both sides, clockwise and anti. If the wheel so much as moves 2mm froe or aft, this will be your problem.
On the Cossie, the problem was resolved by fitting much hard nylon front ARB bushes.
Hope this helps!