Before valve stems rip, they lean.

[APenNameAndThatA]

 The problem is tyres rotating on the rim with the tyre spinning up on landing or on breaking. It is an argument in favour of running maximum pressures. Does this mean that the valves should be checked and rotated back before a big trip? Spose not. This caused rapid air loss. Solutions or prevention? Should the tyre be glued to the rim? Breaking the bead was only a little difficult.  

Edited October 10, 2022 by APenNameAndThatA

[facthunter]

Shellac dissolved in metho will glue the tyre to the rim. satisfactorily. Nev

[onetrack]

You should run the manufacturers recommended tyre pressures to help eliminate tyre creep. Tyre creep is usually caused by heavy landings as the tyre has to overcome the inertia of the rim/brake assembly as it spins up.

You can put a marker line on the rim and tyre with a paint marker to check for tyre creep. If the valve is angled as shown, there's a good chance another heavy landing will tear the valve stem where it attaches to the tube.

Facthunters suggestion is sound, you can also aid the tyres grip on the rim bead area by roughing up the bead seat area on the rim, with some coarse emery cloth, or a flexible sanding sponge pad.

Also, upon assembly, ensure the tyre bead is cleaned with a plastic kitchen scourer and some detergent, and then washed clean, to ensure there's no tyre fitting paste on it.

In addition, new tyres have a factory coating of mold release agents (rubber release) which are slippery and soap-like. Removal of the mold release compound will remove any bead slipperiness.

 

Edited October 10, 2022 by onetrack

[facthunter]

Glycerine doesn't harm rubber, cleans and is water soluble. Don't use silicone or Armour All. With a solid wheel use tubeless tyres with the bead stopper design. Some rims get drilled and short self-tapper into the rubber of the bead not deep enough to damage the steel wire.  Chromed rims are too slippery. you'll always have trouble with them. Nev

[APenNameAndThatA]

Excellent info. Thanks. I think you are right about the heavy landings. Someone said to me that it was breaking. Breaking and landings would both have the same effect on the tyre but landing heavily would both cause more acceleration and give the opportunity to shake the tyre off the rim. Ripped valve stems are a big enough deal to make the extra bother really worth it. This is also an argument against the indiscriminate use of baby powder.  

Edited October 12, 2022 by APenNameAndThatA