first thing insurance will check is your wheels,that is a routine inspection that they carry when assesing damage on the car, so if you are runing non standard size wheels you may be in trouble already.when you are trying to improve 'modify' your car you should do it properly and safe and not worry too much about if it is legal or not, otherwise just keep it stock. it's not worth the headache! your car would have to be really f...up... so they would think of canceling your policy.