Whats the difference between AO, MO etc etc tyres, as far as i know it means audi only, merc only etc. This being due to different sidewall construction/rim protection for different manufacturers.

Now this is where the confusion seems to arise, if you have an audi a3 on "AO" tyres all's good. If its on normal not manufacturer specific then it's all good. But say you had the same audi a3 on "MO" tyres, would this then be an MOT failure as "not fitted in accordence with tyre sidewall instructions"

Any input?