I found a nail in a tyre that is fitted to our 2005/55 low mileage Renault Clio. On taking it to the local tyre depot the fitter on examining the tyre stated that although the puncture could be repaired the tyre was in fact perished due to "cracking" around the edges of the tyre where the tread pattern meets the tyre wall. Whilst I am all for safe motoring I pointed out that there was good tread depth and the vehicle had in fact recently passed an MOT test without any comment being made. I then asked him if he couldn't or wouldn't repair the tyre, he then became evasive and consulted his supervisor before repairing the tyre, (it seemed that he was pushing to sell new tyres). I then examined all the tyres on that vehicle and on other cars including some emergency service vehicles and found them to have the same "cracks". My question is was he trying to make a sale or are tyres in this condition illegal?