Undeniably handy & useful 14 mm (11/16″) Easy to reach Used for frustration abatement Here is a handy and useful little item; a bent valve stem for tubeless scooter tires, (or ATV tires, dirt bike tires, go-kart tires, or just about any other kind of tubeless tire) The diameter where the stem mounts is 14 mm, which translates very close to 11/16″ in non-metric measurements 30 Day Warranty Description Here is a handy and useful little item; a bent valve stem for tubeless scooter tires, (or ATV tires, dirt bike tires, go-kart tires, or just about any other kind of tubeless tire). The diameter where the stem mounts is 14 mm, which translates very close to 11/16″ in non-metric measurements. Straight valve stems have their place, especially on traditional bicycles wheels. But they can be frustrating where space is limited. Now you can practice proper frustration abatement with an angled valve stem, (and maybe fewer skinned knuckles as well).