I'm looking for a trye tread cutter if anyone has one lying around.

I'm after one as well, i looked ebay they're big money new

haulage contractors use them to recut commercial tyres if you ask a local contractor he may let you use one on the premises

Couldn't you make one?

A mate of mine and myself made one about 20 years ago, but then it was only ever used on landrover tyres so didn't need to be that accurate!

this might help,
http://www.gt-4.co.uk/specialoffers.htm

I've got one you can borrow, I'm in Ghana at the moment but hopefully I'll be home on Thursday.

I stay just outside Cupar.

Cheers
Davie