21 inch tube on a 17 inch rim???

[trophydave]

It may seem a stupid question but can you somehow use a 21 inch inner tube on a 17 inch wheel?I seem to remember reading somewhere that you could do it.It would mean one less thing to carry in the spares dept.

[guest295]

Better to do the opposite. A big tube on a small rim will have folds, which will work their way into a puncture. Use a 17" tube and let the rubber stretch.

[trophydave]

Cheers,I forgot to say that it would be as an emergency get you home thing,not for riding around on normally.

[guest146]

That would not be a good idea. For a start where its folded it could run hot and if you had an accident and was found out you for the high jump. As someone said you may get  away the other way round. or better still carry a can of sealant as an emergency

Ken

[Andy M]

You probably heared this somewhere like the HU site? The theory is you only need to carry one tube. As stated above it'll work. It'll work with any kind of puncture including thorn in the sidewall types that goo won't fix. It'll work just fine at 15 psi and 35 mph. The problem is that at 70 mph it might well explode and ruin your day. For Europe the gloop is safer. Outside Europe I'd carry a tube for each tyre plus a patch kit with the idea of only taking a wheel off once per puncture. If you are in some sort of event that involves going in circles where the weight of a second tube is an issue, you might want to use this as a strategy.

Andy

[trophydave]

I think it was the HU site where I heard this.Tempting fate but it is many years since I have had a puncture and that was back when I had bikes with tubed tyres.Twenty odd years on tubeless tyres with no problems except the odd leaky valve and a corroded rim that wouldn't seal properly.However I have had the Transalp for about 18 months and so I am back on tubed tyres.I think that I should carry some puncture kit/tubes/levers even if only on long runs.

[Andy M]

I've had 4 punctures in 16 years riding, 3 of them in the space of 11 months 

I'd suggest you play with your wheels, tyres seem to be aimed exclusively at tubeless configurations and rims vary a heck of a alot. The result is three different experiences with very similar tyres. My Dads Guzzi had Pirelli's marked Tube type that were so tight we had to use a hacksaw to get them off and get a tyre place to fit the new ones. The Bonnevilles OEM tyre is a TT Bridgestone that you can get off with some serious pressure so long as you soaped the rim when you fitted it. I'm now using a Heidenau M+S rear for winter stuff that goes on and comes off with nothing heavier than a size seven boot and a couple of tea spoons. Knoblies seem easier to work with.

Now TL tyres on spoked rims a la BMW F650, don't get me started on those.....

Andy

[guest146]

What they tend to do these days is put a lip or bead around the rim close top the rim edge. If you do get a flat it holds the tyre more or less in place on the rim so avoiding an accident. Its this that makes not only motorcycles but cars anf trucks so hard to remove without a bead breaker.

Ken