Rim and Tire sizes
 

2008 335i Cabrio Sport Package

Staggered 225/40 255/35 /18"
Are the rear rims actually bigger in size to fit the 255 or is it just tires itself? can i swap out the two types of tires and put 235/40/18 Dunlop winter tires all around on the 4x rims and not have any problems?

stocks?

The rear rims are just wider... front are probably 18x8 and rear 18x9 (guess)

You can use those 235/40s but the rears may have bit of a strech, not really noticable though. Check with e90post.com

since the overall diameter of front and rear are the same and the rims are only half an inch difference in width, use 225/40R18 all the way around. u'd be hard pressed to tell which rim is front or rear. no stretching required guaranteed and narrower winter tires gives better traction in snow.

thanks!