These are a bit lighter than some other brands, though probably not by a huge margin. They do have removable valve cores, which is not that common. You can use a sealant like Stans in tubes too. Your tire may still flat, but you might only have to re-inflate rather than replace the tube. I have also bent the little core stem on other tubes and had to replace the whole tube. Could have just replace the core on these. I find they hold pressure pretty well, maybe a loss of 10psi or so over a few days. You should check your tire pressure before every ride anyway.