Hi all. I have just sold my series 3 and acquired a a 96 sportrak with a gen 60k on the clock. It has 225/70/15 continental contrak's fitted and they are poor at best when off road. Now what size tyres can i go to on these alloy rims as i would like a more comfortable 70mph cruising speed (less rpm)and a more aggressive pattern for off road. will i need to go up a rim size to do this the car has standard suspension with no lift so I cant go to big with them.