The older RWD wheels use a different inward-outward offset, but the bolt pattern and centering are the same.

I am currently using a set of RWD wheels as my winter wheels and they work fine. In the back they make little to no difference, but in the front they change the turning circle a bit. I'm sure this probably also subtly changes the suspension geometry as well, but it will be small.

Here is a chart that shows the various bolt patterns and offsets Volvo has used over the years:
http://www.custom-wheels-spinning-rims.com/Volvo.htm
(ET is offset, and I'm not sure what the letter codes M and H actually mean in mm...)

This page says that the older RWD wheels have an offset of +20mm or +25mm.

This page says that the newer FWD/AWD cars use an offset of +35mm or +38mm, while the 'R' wheels are +46mm)(!!).

One thing to consider is that the RWD wheels are 'thinner' than the newer wheels (16" vs 16.5" according to the earlier linked-to chart) so the actual edge of the tire should be in roughly the same place.

If the offset is really WAY out there on your RWD wheels you could be placing a lot of extra strain on your wheel bearings, but lots of folks do it, esp for winter wheels.



--
1998 V70 AWD->FWD Turbo 200k+