davey_b

Currently have factory fitted 21 inch alloys on my S8 but looking to get another set of alloys to put winter tyres on and then just swap them over when required. Would a set of 18 or 19 inch A6 wheels fit?

MP4.2+6.0

Not a top choice probably. The A6 is sort of its own group now with very conservative offsets, meaning the wheel would be tucked in pretty far. Would want to watch inside clearance issues if they are wider, though A6 wheels only usually go to 8 ½'s I think. If you want them in a lot for less crud on side of car and you are reducing tire width, then maybe.

The Gen 1 Q5 offsets are similar to D4, and that's the biggest Audi seller now for years as far as wheels out there. Springs off of the A5 design, which also makes S5 a good donor. If you want 9" wheels, they are likely S5. Q5's are narrower, compatible offset wise to D4 for general look. OR, the base D4 A8 19's that are sometimes actually out there too. They tend to sit in the marketplace, at least in USA, so you might look for some. Low volume though.

Start with tire width and go from there. If you are going narrower (starting at 255, but then down into 245 or less), you want to be moving the wheel width down. You have to stay in last 6 or 8 years of designs BTW to have the current Audi hub center norm. S5 and Q5 are both there, D4 is of course, and for A6 it has to be the most recent C7 series. No C6 or D3.

davey_b

Thanks for that. I'll have a look at things and try and work out what my options are. I'm basically just looking for a fairly inexpensive set of wheels that I can refurb myself and then fit with winter tyres for when the snow starts. Currently on 21 inch but happy to for down to 17 or 18 inch if required.

MP4.2+6.0

Need to look at 19 and up. S8 brakes at 400mm won't clear less than 19's. Since it is generally tight at 19, the barrel and spoke shaping need to be correct for the calipers. In USA, Q5 19's are/were commodities with people aspiring to 20's, but even entry Q5's are higher end here. Small market, but 19's for D4 A8's are similar here. Again, decide on tire width early, since wheel width should match up. If like me you are in a more cyclical snow area/mountains where it comes and goes and you still see a lot of dry pavement in winter, standard D4 widths might be used with more of a performance winter tire. If you are in a long winter/lots of snow and ice crud on roads for long periods, many step to a narrower width and more aggressive tire to cut through that crap with weight focused on narrower tread. Fortunately, being August, you have time. I can usually find a decent set of OE wheels for what I want at a good price if I just keep looking at the normal places with used wheel postings for a few months.

davey_b

Sorry phone changed A8 to S8! I actually have an A8 SWB. How does that change things?

PhillyVance

Not much difference my old D4 A8 had 380mm brake rotors. I wouldn't go under 19's. Where do you live? I got around with no problem in philly with all seasons for the last 3 winters.

davey_b

I'm in Scotland but live out in the sticks so winter tyres are a big help

MP4.2+6.0

If you have 380 mm brakes, you can probably go down to 18's. My D3 A8 W12 had 385 mm brake discs, and it could (just barely) fit 18's. As a generalized statement, 18 and 20 inch usually have more tire choices and/or better pricing than 19 and 21 as a bonus. 18 opens up yet more base sized type wheels in similar offsets too--Q5, etc. per prior reply.

I didn't cover it in prior responses, but just to avoid an issue, also skip generally the transverse engine ones--either wheel offsets and/or hub centers will be wrong (A3, S3, tt, etc.), but the wheel design capacities also seriously under the D4 weight.