Radial Tire Inner Tubes


Ed Price

John talked about the desirability of having a safety bead in your tire rim (for
an Amphi, mainly to keep the tire on the rim if you get a deflation at speed),
and that you should always use an inner tube with radials on an Amphi rim (since
the Amphi rims do not have a safety bead, and strong cornering may cause sudden

I started thinking about what kind of inner tubes are needed, so some searching

"RADIAL-TIRE TUBE: The construction of an inner tube for use in a radial tire
differs from the tube used in a bias tire. A radial tire flexes in such a manner
that it concentrates the flex action in one area and at the edge of the belts in
the shoulder of the tire. This concentration of stress will damage a standard
tube causing it to fail. To overcome this problem, the radial tube is made of a
special rubber compound that is designed to overcome this concentrated stress;
Therefore, standard tubes must NEVER be used in radial tires. "

"California DMV; Inner Tubes; Section 27455.
(a) On and after January 1, 1975, no person shall sell or offer for sale an
inner tube for use in a radial tire unless, at the time of manufacture, the tube
valve stem is colored red or is distinctly marked in accordance with rules and
regulations adopted by the department, taking into consideration the
recommendations of manufacturers of inner tubes.
(b) No person shall install an inner tube in a radial tire unless the inner tube
is designed for use in a radial tire. "

So make sure that, if you use radial tires, you are also using radial-rated
inner tubes!

El Cajon
67 Rust Guppy

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