I would never mount a rubber mounted 90 degree stem on any tire. They are plain dangerous unless the rim is designed for it. Those designed for it have a clip that attaches to the stem to keep it from flexing.
The 90 degree solid mount stems are not an issue if correctly installed.
The 90 degree solid mount stems are not an issue if correctly installed.
Last time I tried a 90-degree stem, I had a catastrophic loss of pressure. Seems the centrifical force tore the new stem away from the rim. I admit that it was a rubber stem, but don't know that I'd feel that much safer with a metal one. My shop won't even install them anymore and actually pulled all the valve caps off the shelves that had any significant weight to them - you know, the ones that look like an eightball or dice or whatever - even the caps that are designed to show (green/yellow/red) the current pressure.
I'm looking to get the Orange Electronic TPMS with the internal sensor to prevent them from being stolen. I'll have the shop install them. Looks like I'm going with the M202 version.