Converting to B4 wheels can get complicated.
Front axles your need:
associated part 6801 RC10 front wheel conversion.
That was easy, the next bit is complicated.
For the rear axle you have choices.
Dogbones or CVA?
Dogbones you need: associated part 6802 RC10 rear wheel conversion. plus dogbones part 6370 x2.
Bare in mind the toe-in will now be wrong. original cars had 1.5 deg arm mounts and 1.5 deg hubs. for a total of 3 deg.
older cars had 1.5 deg mounts and 0 deg hubs.
ReRe have 3 deg arm mounts with 0 deg hubs.
Basically if your left hub has a big "L" on it. Its 1.5 deg. if it has nothing it is 0 deg.
arm mounts are not marked
Fun huh...
The CVA way you need. part 6371 CVA 3/16" axle.
plus hubs, 7364, plus arm mounts 6360 you still need bearings, crush tube and the nasty blue spacers. 3977 (3/16 x 3/8 x1/8" bearing) 7377 crush tube. 9608 axle spacers.
Now you put all that on as in the worlds ReRe manual, and you find out that Associated made the axles too short. The proper way to fix is using B44.2 rear centre axles which are the correct length (2mm longer) part 9911 (discontinued).
There are other ways to do this using 3/16 x 3/8" flanged bearings gets around the hub issue, but those bearings you will need to get on ebay.
You just spent 100 euros because you will never find everything in one place and the shipping just keeps adding up.
Trust me learn to like the 5 spoke rims!
Mark Rogers (top Ausi driver) posted a photo ( Facebook, RC10 vintage mania group) of his RC10 graphite with 5 spoke wheels and it looks AWESOME!!! (sidewinder body helps!)
Schumacher do a few 2" tyres.