Can you find where the leak is? Airing up your tires before each ride? Checking for foreign objects stuck in the tire?

I use road tubeless on my main bike, but have regular tube clinchers on my other RB. They are Continental tubes, and have been on the bike since July 2009. (I don't ride this bike that much except in the winter, but I wouldn't hesitate to take off on a 100-mile ride with these tubes.) I've had good luck with the Continental tubes.

All the tubes I've bought have had threaded valves. I'd guess the pump nozzle would "grab onto" these better than non-threaded valves. Just guessing, as I've not had the option to even buy non-threaded.