I know that you can't mix cross-ply and radial tyres on the same axle (and if on axles then radials have to be on the rears) not that this applies to our 75/ZTs.
The MOT should rightly flag if you've got different profile or sizes on the same axle, same with rotational tyres fitted to the wrong side. I suppose if they want to go to the letter of the law they could check the speed rating as well. I'm not sure about if you put a car in with a steel full size spare and remainder alloys, if the tyre is the same size, profile etc.
I've always made sure that I've had matching tyres across an axle, it makes sense and you can see why it would be safer - you wouldn't want a 2mm tread on the same axle as a brand new tyre with a completely different pattern - differing levels of grip etc. Probably more so with front wheel drive. I have seen it suggested somewhere that the new tyres should also be fitted to the rear axle (assuming you're only changing a pair) for similar reasons.
On other cars, if I have had a mis-match of tyres I've kept the best of the rest for the spare and fitted a matched pair, the only time this was no help was when the only good one was a rotational tyre so no good for an all round spare.
|