[davyk31]

I have an E70 X5 M sport running on 20" for summer and have gone to 19" for winter. I chose the 19" SE wheel as the 5 spoke design would be so much easier to clean in winter.
All fitted yesterday but the new wheels sit in a lot further especially exagerated by the fact that my car has the extended wheel arches due to having the 20s as standard.

20" wheels are front 10x20 ET40 , rear 11x20 ET35
19" wheels are front 9x19 ET48, rear 10x19 ET53

I was referred to a comparison site which gave the results with the 19s fitted :
Front : inner clearance 5mm more, outer position retract 21mm
Rear : inner clearance 5mm less, outer position retract 31mm

Does this mean I need 20mm spacers front and 30mm rear to get back very close to standard? Can someone confirm these numbers from the calculator are correct please.
Also would it ever be ok to just fit rears as they look the worst and thus save a few £££s
If I do fit all round is there any issue with not having the same size spacer all round or do I need say 25mm on all 4?
Finally any advice on buying and where to buy? seems the ones that bolt to the hub are best to avoid needing new bolts and lock nut etc.