SORTED: Thanks to all for a rapid response. If I wished to put two different sets of the same size tyres with the tread depth within +/-1mm fitted front/rear on the Defender, which is full time AWD with locking centre diff, would this pose any significant problem with increased wear and tear? The 2 sets are both road tyres, with similar compounds and tread pattern, just different brands. Assuming proper tyre rotation I'm hoping this will be fine(?)