What 15inch wheel rims would replace 220/55VR390 rims on a 1985 735i BMW?

[M333]

For a 15" you will want to find one with a 18mm offset, a 5x120mm bolt pattern, and put a 225/60-15 tire on it.

There are a lot more 16" available, at least from Tire Rack. Then it would be a 20mm offset, with a 225/55-16 tire. The V in VR is a speed rating, and would be used for these sizes as well.

[M333]

For a 15" you will want to find one with a 18mm offset, a 5x120mm bolt pattern, and put a 225/60-15 tire on it.
There are a lot more 16" available, at least from Tire Rack. Then it would be a 20mm offset, with a 225/55-16 tire. The V in VR is a speed rating, and would be used for these sizes as well.

[M333]

For a 15" you will want to find one with a 18mm offset, a 5x120mm bolt pattern, and put a 225/60-15 tire on it.
There are a lot more 16" available, at least from Tire Rack. Then it would be a 20mm offset, with a 225/55-16 tire. The V in VR is a speed rating, and would be used for these sizes as well.

[glock]

I asked recently about fitting 15inch tyres to a metric size wheel, tyre size 220/55VR390, and all of the advice I received was against the idea and said it couldn't be done. The only option left is to replace the rims to take a 15 or 16inch tyre. What other BMW rims would fit a 1985 735i BMW?

[Mach2]

Why 18mm offset for a 15 inch wheel M333? You can run anything from a 12mm to a 26mm offset with 20mm being the most common.
Like I said earlier it is best to simply find a wheel from an E34 5 Series or E32 7 Series. These have the correct offset, bolt pattern, and hub diameter.
You can source from any 5 and 7 Series except you will need hubcentric rings if sourcing from an E39 5 Series. 6's and 8's are also good sources but the 5's and 7's are more common and there is more selection.