Would agree just worked out the overall height of a 225/55/16 to a 225/40/18 the 18 inch wheel and tyre assembly is 1.6 cm taller so negligible differenceThe rolling radius of a set of 17's is the same as tbe 18's no bigger overall it will be just the offsets but there should be no issue you may still need spacers for the rear if its a pre facelift 2.8