Hi all can any one tell me the reason for my front tyres on my st line 66 plate fiesta wearing more on both  edges 3.5 mil on average in centre 3rd of both front tires down to 1.5 to 1.0 on outer and inner edges on average, I regally check pressures and have the recommended pressures in my tires and I don't drive around corners with tires squealing, these are the original continental tires fitted new and have covered 20800 miles.

Tracking?

could accept this if it was on inner or outside edge but not on both edges.

If there the premium contact 2 they have primary and secondary tread the secondary tread is shallower than the primary tread but are still road legal as long as the primary tread is 1.6mm

looking on line they call it shoulder wear and says it points to underinflated tires but mine have never lost more than the odd pound of pressure between checks and have been run with the recommended 33psi in them.

I had Continental sport contact 4 (i think, or maybe 5) on my 2016 St-Line . I had no problems with uneven wear and I kept my pressures at 33 front 26 back for most of the time unless the car was fully loaded, then I pumped them up to the recommended pressures as shown on the sticker on the passenger side door pillar.I think the fronts only went up a slight amount but the rears jumped from 26 to something like 38.

Are you regularly driving a fully loaded car? Are you sure your tyre pressure gauge is accurate, I have seen some cheap ones attached to foot pumps that are over 8 psi out.

If you are sure the pressures are correct for your load then get the wheel alignment/suspension checked out.

When I got rid of the car at 31,000 miles the fronts still had about another 10,000 miles left in them based on the wear from the previous years.