Had my Volvo MOTed last week and got an advisory on the front tyres (down to 3mm). I have Pirellis all round so had a look at Pirelli prices online and ASDA of all places came up cheapest (£10 per tyre cheaper than the next cheapest). I didn't even know they did tyres. All you do is book through their website and choose a fitter from a selection they have in your area. Ironically, I will be getting the tyres fitted at the MOT place I use anyway, but cheaper than they would be able to offer direct.