> OK, for me this begs the question: What is the difference between
> a normal "tubeless" rim and a "safety" rim?
Can't find a photo on the web offhand ... the difference is an extra bump of
metal around the rim, about 3/4" or so away from the surface the tire bead
seats against. Sometimes, not always, it can be seen as a dimple from the
outside of the rim on pressed steel rims.
Once the tire bead is stretched over the bump during installation, it's less
likely to move back past it if the tire is driven flat. This keeps the bead
from dropping into the center depression, and so helps keep the tire on the
rim during a blowout (or being driven severely underinflated). In theory at
least.
BTW, it's also a common misconception that safety rims have anything to do
with tubeless tires ... they were originally developed for tube-type tires
(which are much more prone to suffer sudden blowouts than tubeless).
Randall
|