I am about to install the 90 degree valve stems and was wondering where the O ring goes, on the inside of rim or the outside. My money in on the inside but I have been wrong to many times in my life and this is rather important!
Look at the stem carefully.
The 10mm Aluminum Valve Stem 90* (https://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3A10mmAVS) I sell have a groove in the stem for the o-ring. It puts the o-ring on the outside of the wheel.
Yours might be different, unless you got them from me.
Randy - RPM