[Geoff Winnington-Ball (RIP)]

Reckon we'll just have to see how it goes with the tyres & rims the lads have standing by. It might be an opportune moment to reintroduce for review Mr. Notton's original post on his technique:

British v Canadian rims and fitting

Its a bit incredible that we went to war with two identically defined tyre sizes that are actually different, all is not lost. The difference as far as I can determine is the tyre bead angle, everything except the Canadian is a 5º bead (to the horizontal or axle line), the Canadian tyres are 0º, theoretically this makes the Brit ones easier to get off as they become sloppy on the rims with the smallest movement away from the rim edge.

We have heard the tales of rim machining to ease the current types onto Canadian rims and people shaving off the inner lip of the bead with a utility knife, but its not really needed, the bead on modern tyres seems to be quite flexible enough to fit but it is a struggle. Here's how we have done it several times over on a F15 with various current manufacture 9.00x16's, let me stress its our way and I am not advocating or recommending the method which has its dangers if extreme care is not taken as I hope will be patently obvious.

Once on, the 5º bead angle tyres WILL need a hydraulic truck sized, four arm bead pusher-offer of substantial grunt to remove them again, you will never get them off at home.

You need an extra pair of understanding, strong, competent hands, don't for one moment think wife/girlfriend/lad next door can lend a hand when needed.

Clean, shot-blasted, painted rims are an essential starting point, just getting the tube and flap in a new tyre is difficult, the beads are always sprung together, whichever way you seem to fit these the flap hole, valve, or both, always seem to be pointing the wrong way no matter how hard you try to deduce where they are going to end up, the flap often gets slightly too far round and needs taking out to stop it pulling the valve sideways.

You need a lot of rubber lubricant - washing-up liquid contains salt and will rust the rim, Vaseline/petroleum jelly rots rubber, we have used Hellerine - a commercial rubber lubricant used in the electronic industry for fitting rubber sleeves on wiring, its made by Hellerman; this stuff is thicker than 90EP and twice as slippery. You will find a air impact wrench almost vital for spinning the split rim nuts on and off unless you happen to be Mr Universe. You will get very hot, very angry and totally filthy.

Get the tube in and give it a little air, valve core removed, to open the beads and see where the valve settles, get plenty of lube up the inside of the bead for at least an inch, struggle with the flap and get it all in then add a puff of air again and see all is sensibly lined up, it probably wont be too well.

Really, really lube the bead; really lube the whole of both the inner rim faces that form the well right out to and up the rim edge. Lots.

Put a long brass extention on the valve, it will disappear if you don't, place the tyre on the inside rim as square as possible, it will only just sit on it, put the outside rim on and start the two long rim studs, pull them down enough to start all the rim nuts by nearly half depth. Don't over-do it you WILL pinch the flap and tube somewhere.

Put a _little_ puff of air in, just enough to make the tube take shape, and with a mirror and a bit of flat wood inspect between the rims and encourage the flap, by pushing with the wood, to centralise itself and go up into the tyre a bit, but don't over-do it as the flap will pop out elsewhere.

This bit is POTENTIALLY LETHAL and intrinsically UNSAFE - BE WARNED.

Ensure you're happy that the two long studs have a sensible amount of thread engaged and all the rest have at least two or three turns on them, all should be just bearing on their seats. With the valve core still out to allow instant deflation, GINGERLY, inflate in short bursts until you see the beads start to move up and out along the rim, it takes a moment, give it time and NO MORE THAN 10 -15 psi, as soon as this happens remove the inflator immediately.

The rims will likely now fall together when it deflates which is a good sign, to be certain, lever them apart and inspect with the mirror to see the flap is now properly up in the tyre and will not get trapped anywhere. Torque the split rim nuts down fully and inflate, the beads will pop out fully onto the rim edges at about 20 - 25 psi, remove the extention piece and fit the core, bring the tyre up to about 50 psi and check the side wall concentricity rings, a few hearty thumps with a hide-faced mallet usually corrects any slight anomalies.

If you can't immediately visualise what I've described and how to achieve it, then I make the only recommendation herein, which is that you should NOT be doing this at all.

Richard
(Southampton UK)