Terios rear tyre wear


Hi, I put 4x new tyres on our 09 Terios 10 months ago and have done around 11,000 miles since.
The front tyres hardly have the moulding spikes worn off but the rear tyres are nearly down to the wear bars on the outside edge, probably half worn on the inside edge.

Any reason why this should be? and any recommendations for a good replacement?

Many thanks