> We've always used tubeless 155/80 13 tyres on our Herald wheels with no
> problems, but recently when we've been having tyres fitted we
> have been told
> that it's dangerous to run them without tubes on these rims
> (something to do
> with the rim shoulder being too narrow and the tyre may slip
> off).
Nonsense !
The same story made the rounds about original TR3 wheels some years ago ...
the issue is that the rims lack a feature called a "safety bead" that was
incorporated on newer wheels. Tubeless tires are more apt to develop a slow
leak than tube-type tires, and there was a concern back in the 60's that
people might continue to drive their tires with almost no air in them.
Under those conditions, the safety bead helps (somewhat) keep the tire on
the wheel. Here's a web page with a drawing of a safety bead :
http://www.diamondracingwheels.com/TermsSafetyBeads.htm
So yes, driving on these early rims might possibly not be as safe as modern
ones (especially if the modern ones are mounted to a Volvo) ... but saying
it's safer to run tubes just completely misses the point. It's not safer to
run tubes, rather the safety bead is just a further safety development
beyond the tubeless tire.
Kind of like air bags being a development beyond seat belts, it doesn't mean
it's safer to not wear a seat belt in a car without air bags !
Randall
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