New answers tagged valves
If the grommets worked with the tubes they should work with Stan's conversion kit. The kit is really just a wheel side tube. The kit is thicker rubber than most tubes. Unless the grommet extends a long way on the inside I doubt it would cause the kit not to seal. The Stan's web site has a list of compatible tires. Recommended Tires
One way to solve your problem is by doing the ghetto tubeless method with the 20 inch tube. The other method, with the gorilla tape should be possible as well by cutting a valve out of an old tube and leaving enough contact material with the tape. http://www.pinkbike.com/news/Tech-Tuesday-Gorilla-Tape-Tubeless-Conversion.html
I mean, put enough Stans in to the wheels, and you can run tubeless on just about any rim setup. If you have non-tubeless tires, you may run in to an issue with the tires themselves being too porous, and that is hard to get around. But I imagine that the combination of rim-tape, grommet, and Stans will be fine. The rubber wedge/plug thing on the base of ...
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