I have found that the extra heavy duty tubes with Ride-On in them (regular tubes are about 1mm thick, the super heavy duty ones are 4mm thick. Ride-On is a sealant made for motorcycles, and is a lot more expensive than Slime, but works a lot better) will stop most puncture flats. Nothing I know of will stop tire damage from running over glass or sharp metal. I use Windex to install tires, so powder won't work.