I was inspired by Brents tire 'machine' posted elsewhere as I still do the back breaker either on a piece of old form ply or a shitty old road tyre I've had for years.
One of the hardest tyres to remove is the 20 or 30 year old knobby that comes on just about every project bike we ever buy and ages ago I got sick of buggering up prefect good ? old rims just to remove a crappy tyre destined for landfill so here is my way of getting the tyre off with out damaging the rim but be warned as it can end in tears (and the back of an Ambulance requiring 40+ stitches)
After the usual valve removal and rim lock release break the bead on both sides and then get a sharp Stanley knife and cut through the sidewall as close as possible to the rim using afew shallow cuts rather than on real hard and deep one, but be bloody careful and NEVER cut towards you or it will be a trip to hospital FOR SURE ! If you are intending reusing the rim locks just use common sense when cutting over them.
Once you have cut all the way around the case will just fall off and then if you want to it can be cut up and binned.
The final step is to arm yourself with a good set of decent sized bolt cutters to chop through the bead, which will if the cutter head is in good shape and adjustment cut it in one go. Of course the old tube will be collateral damage but who uses 30 year old tubes anyway? (yeh - I bet someone out there does so own up!!!)
EASY - but please exercise GREAT care with the knife !!!
Dave Mac