Been running Crest rims tubeless for over a year - I wonder why anyone would still want to run tubes - reduced weight / rolling resistance, lower pressures and better grip for starters. 1 puncture in 12 months due to glass on the road which would have shredded any tyre. So impressed, I built some P35 rims and can run 2.4" tyres at less than 16/18psi tubeless - floats over loose sand and I can get up climbs that leave everyone else scrabbling behind. Great success with Conti X-Kings and Race Kings - the basic, folding ones work fine.