its a 99 civic and ive been having problem with my tires they dont last at all... the car is sittin on 17 and 205 40 17.. the car is lowered and i kno the rims are too big so im buying the rota track r in size 15 but they come in 15 and 40 offset ... so my question is what is the best offset for t and what is the difference between these two ofsets .. thanxx