Which size should I buy for my A4 ,I will be putting a 1.3 inch drop on the car.Should I have any rubbing concerns? Will the 225s or the 235s have a lower profile sidewall ? Thanks CM

not if u have a hard suspension set up tha 235/40/18 shud be fine

the 225's will have the lower profile sidewall. 225/40 means that the width of the tire is 225 mm, and the sidewall height is 40% of that, or 90 mm. the 235/40's will have a sidewall height of 94 mm.