36" Tubes: Valve Stem Sizing

After building a wheel with the Stealth2 rim I tried to install the tube from my Coker wheel (current version). When I couldn’t I noticed that the valve stem is tapered and the base larger than the normal bicycle schrader type. The Coker’s valve hole was also larger to accommodate this. Thinking that Coker used their own tubes I ordered a replacement from UDC which was stated to work with all 36er’s. However that tube appears to have the same valve sizing and also doesn’t fit in the Stealth2’s valve hole. So what is the deal? Is the Stealth2’s valve hole sizing different from the other UDC brand 36" rims? Was it designed for 29er and Foss tubes only or something? None of the UDC sites seem to mention it.

I guess I’ll have to drill it out?

Thanks for any info you have…

Drilling wouldn’t be a big deal, as you already a spare in the larger size. It would just mean the need to shim if you ever went to a tube with a smaller valve.