18" option tires on 330Ci

[youngn3]

Hi, I have a '04 330Ci with the 18" tire option, where the front and rear tires are of different sizes. The front have 225/40ZR18, the rear have 255/35ZR18.
My questions are:
1. can I still rotate the tires, how?
2. can I replace both front and rear with the same size later? all 225/40ZR18 or all 255/35ZR18? are the rims the same size or are they actually different?
Thanks.

[Silver4evr]

Rotate your tires side to side. Here's a link confirming this.

As far as future purchase, ask the dealer about exact rim size and if the suspension is tuned to the OEM tire size and if putting the same size tires all around is recommended or does it void your warranties or cause some other suspension problem.

[youngn3]

Oh, I forgot to mention that they are all directional tires.

[Silver4evr]

Oh well, I guess you answered your own question.