I have done as much research as I can and I think I know the answer. I need new wheels on my E55 as i found them cracked and bent by the prior owner I saw a set of E63 wheels for sale locally. They are from a 2010 though. I don't think I can use them because the offset is a fair amount greater. Here is the info I found:

E55 Front offset 30 Rear offset 39
E63 Front offset 37 Rear offset 52

The rear is a fairly large difference. I can't see using 13mm worth of spacers to get it to fit and look right. But, I cant figure how that would all work because the rear wheels on the E63 are 9.5" vs 9.0" Would I need spacers? Can I get them to fit???

 

I have run 285/35/18 tires on 18x9.5 et45 rims on my 55 rears and there was still some space on the inside before tire would interfere with suspension component. If you use 275 tires then pretty certain 52mm would be OK.

If you add spacers they must be at least 8mm thick to clear the ~7.xx mm rear hub lip to then allow use of hub+wheel centric spacers. To maintain factory handling characteristics would recommend replicating or getting closer to stock offsets. There are a couple of shops that fab any thickness spacers, hub+wheel centric, for $50 or $60 a pair.

 

I did some more math. I think the front would be more of an issue. The fronts are 9" compared to the factory 8" That would require one heck of a spacer! I think I will have to pass on them I would have liked the extra .5" on the back though

 

I run 275 tires on 9.5 et 35 on fronts. Handles very well. You can keep the 37mm offset or add up to a 7mm spacer, which is by no means a big spacer.