[SOLVED] Does anyone know what thread size a tire valve stem and the Schrader valve are?

replying to Wally, Verlyn Foster wrote: You can obtain a T handle valve stem tool at any auto parts store. These have the capability of internal and external thread repair as well as an easy out for broken valve cores.

5/32-36

I finally bought 4 and put them everywhere so I could always find one of the damned things.

4x 4 way Valve Remover Cores inside Car Tire/AC Plug Stem Installer Repair Tools | eBay

I think the outer thread is nominally 0.303" or 7.7mm by 32 TPI. A

5/16" x 32 tap cuts a thread that fits somewhat loosely but well enough, at least to 30 PSI. Valve stem extenders can be reworked if you don't have the tap.

Mike, in Nottingham UK

replying to Wally, Jim B. wrote: By my measurements it is 19/64 (7.54 mm) x 32 threads per inch. I am also seeking a tap & die for such an animal. Jim B.

replying to Wally, Jim B. wrote: By my measurements it is 19/64 (7.54 mm) x 32 threads per inch. I am also seeking a tap & die for such an animal. Jim B.

Metal valve extenders are a cheap source of the male and female threads if you have the tools to adapt them. Otherwise 5/16-32 UNEF does fit, though loosely.

This explains Schrader and Presta valves.

It gives 6 atmospheres as the maximum pressure for Schrader and 15 for Presta, and 0.302"-32TPI as the Schrader thread.

This shows which bicycle thead standards are metric and which are inch.

-jsw

replying to Larry Jaques, Ted Crum wrote: The thread specification for the Schrader valve has almost been lost to history by now. Of course, it is not a metric specification, 32 TPI is not metric. The actual thread is 5/16-32 NEF, with a 80% thread height. Wait, you say, the major diameter isn't 5/16. NO screw has a major diameter equal to it's nominal size - look at a bolt with an unthreaded shank; the threaded part is always smaller than the shank. I bought a 5/16-32 die a while ago and used it to cut Schrader-compatible threads on a .305" rod, and it worked perfectly. There are a lot of bad-fitting parts on the market now, made by offshore firms without the institutional knowledge of archeological bent to get this right.

replying to Larry Jaques, Ted Crum wrote: The thread specification for the Schrader valve has almost been lost to history by now. Of course, it is not a metric specification, 32 TPI is not metric. The actual thread is 5/16-32 NEF, with a 80% thread height. Wait, you say, the major diameter isn't 5/16. NO screw has a major diameter equal to it's nominal size - look at a bolt with an unthreaded shank; the threaded part is always smaller than the shank. I bought a 5/16-32 die a while ago and used it to cut Schrader-compatible threads on a .305" rod, and it worked perfectly. There are a lot of bad-fitting parts on the market now, made by offshore firms without the institutional knowledge of archeological bent to get this right.