[OvalOwl]

I've been driving around with mixed tyres front and back all year. When I got it  there were Vredestein Wintracs on the front and a mis-matched pair of a Bridgestone and a ditchfinder on the rear. I swapped the rears pretty sharpish since the Bridgestone was low on tread and I didn't want a ditchfinder on a Porsche! Promptly lit up the new Continentals on the back and over-steered into a bus.

Same tyre across the axle is what you want, preferably with the same wear. The AA recommend having the best tyres on the rear, since this will cause any failure of adhesion to result in under-steer rather than the more tricky over-steer.