I recently bought some cheap BMW mini steel wheels, these dont fit as standard, the spigot is 56mm on the mini and 57 on the felly. I started with a flap wheel in a drill, which mostly just took the paint off, then hand filing with a half round, which would work but take ages. This method used a cheapy set of 1/4" shaft grindstones (mine were £2.50 for 10 or so from a hardware shop). I was a carpenter in a previous life and have a cheap router (£25 odd several years ago) I thought I'd try mounting a stone in my router.

The wheel was machined from the rear as there is a nice flat where the wheel meets the hub, a spray of wd40 to ease movement on the flat, turn the speed on the router up full, and ground away. Dont do this if you arent confident with power tools, I accept no liability if you wnt to try this, wear safety glasses etc. It worked well for me. I wouldnt borrow your friends expensive router for this as it does shower sparks all over it! buy a cheapy one! Each wheel took about five minutes, running the router round the spigot hole and trial fitting until it fits on the felly spigot.

Dunno how well this would work on alloy wheels, I think the alloy would clog the grinding wheels, might need tungsten ones??

Hope this is of use to people.

The finished wheels fitted on the rat mobile!

that won't work on alloy wheels, like you say the grind stones would soon get clogged up an ruined, it would be easier and quicker to put that wheel into a lathe and use a boring bar on the centre bore... in fact i might get me some bmw mini cooper S alloys and give them a go

a step drill-bit fitted to a pillar drill would be an easy method if you have access to one. ive always done them with a dremel to rough out and a hand file to finish. doesnt take too long tbh

I've seen someone use a router before, but they used a mill bit.

They also made their own jig (just a larger hole) which they bolted to the wheels. The jig took maybe 20 minutes to make but was worth it as they had 8 wheels to do.