Just took the Corsa in for its first MOT which luckily passed with flying colours - apart from an advisory about tread depth on the front tyres. The car has only done just over 11k miles and last time I read the depths about three weeks ago were around the 5mm mark. The garage seems to be implying that the tyres are scrap when the depth gets to 4.1mm. Checked the DOT etc. websites and legal limit is still shown as 1.6mm. Obviously would change prior to that anyway, but a bit puzzled where the garage is getting its idea from (not as if they stand to benefit financially from a purchase of new tyres). 2mm or so of useable tread probably = around another 7-8k miles for fronts. In fact, I was probably more concerned the sidewalls might perish before the tread wore out!