the center bore is different. either you bore out the wheels or get adapters, which can be spacers, in one.

The mpars you have are 72.56 bore and our cars need a 74.1 bore size.

Thanks. What I would like to know what MM spacer I should use? 10MM or 15MM?

Yo need to know the offsets of your wheel to detemine what mm spacer to run, the e38 offset is close to the e39 I think, so you may want to bore them so you dont get fender rub on your tires

I have E38 M Parallels on my E39 528i. They came wrapped with PS2 245/40/18 up front and 275/35/18 in the rear. I left them alone for a year without spacers. I decided to purchase a size down for my next set of tires so therefore a 235/40/18 front and 265/35/18. I ran a 15mm spacer up front and 15mm spacer in the rear. I rubbed a little with passengers(4) in the car in the back and I'm lowered on coilovers. If I were to do it again I would of just left my 275/35/18 tires in the back and used no spacers period.

Spacers put some stress on the suspension parts anyways.

Agreed^^^^^^^^^^Spacers should only be used as a last resort, like if you`re running coilovers and you need an extra 5 or 10mm of clearance to prevent rubbing on the suspension.

Measure...