The nut is more than likely 13/16" which is equal to 20.6375mm - pretty darn close to 21mm, and so a metric wheel brace should be fine to use. Hlaf the time wheel braces have both the metric and imperial size on them.

But perhaps look for an imperial specific wheel brace as the slightly smaller socket might be just small enough to fit.

Try one of these thingos, don't know what they are called.

Useful for spark plugs on a mower and the like. Just throw a long
screwdriver in the cross holes to turn. The wall is about 2mm.

Available at hardware shops, cheap as, different sizes.....

Edit: I remembered the name...."tube spanner"

 

 

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Last edited by EB92 on Mon Oct 27, 2008 9:08 pm, edited 1 time in total.

Thanks for all the replies guys, finally got the wheels off. Was a 13/16" nut, just fits in and had a fair bit of dust on the nuts so a good spray and tap it on with a block of wood did the trick.

Thanks for all your help and suggestions everyone.

a 1/2 inch drive 13/16 sparkplug socket is the best for getting into mags

I've wondered if some mags are made like that to reduce the chance of theft.