since its an x5, i dont think i need to be worried about the tire hitting the inside of the fender, so i measured from the outside of the fender to the widest part of the tire. in the front it was 20mm and in the back it was 35. does that sound right?

the car does have the flared fenders...

ecs, thanks for your help. ill be buying these and the longer bolts as soon as we decide what size!