Stock rim inside diameter
 

I was wondering if anyone knows the diameter of the inside of the rim at the bottom of the U shape if you were to slice the rim in half? I found a picture online and marked what I'm looking for in case that description wasn't clear enough.

The reason why I'm asking is because when I had my snow tires put on the TPMS sensor in one of the wheels was "broken", aka they screwed up taking the tires off, broke it, and wouldn't man up and admit blame or pay to replace it. The sensor itself is fine aside from the valve part being broken off so instead of wasting money on a new one I designed a bracket to mount it via a band on that spot on the rim, I just need to make sure the band I get is the right size and make sure the bracket sits properly on the rim.

Take a piece of string and run it around the barrel, then take it off and measure?

I can't do that because the rims are in use with the winter tires on them, the only time I would be able to get a measurement myself would be when they are mounting the summer tires back on which will be too late since I'll need to already have the bracket and band for them to install it at that point.

Gotcha, I just assumed the picture was of your wheels. My stock wheels have tires on them too, so I'm no help.