i didnt tell them - had a bump - and they didnt notice! sadly clocked the rub marks from the 17's tho. thorough they were , the D**KS! anything that affects the "stance" and "ride" of the car has to be declared. Most dont mind anything 40mm and above - you go lower than that and they'll either not cover you or increase ur premium, but not by that much. If its cornhill dont even waste ur time on the free phone call, they suck ass.