Yes you can run tubes in tubeless tires but most makers of tubeless tires have corresponding models that are designed to be run with tubes, so not much is gained by getting a tubeless tire for a non tubeless rim. .For example, if you like Schwalbe tires but don't have tubeless ready rims, get Schwalbe One clinchers rather than Pro One tubeless. They are very similar tires except for some differences in the bead and construction. Both tires use Schwalbe’s One Star compound but Pro One uses something called microskin to make the tire airtight (when using sealant) while the clincher version has V guard puncture protection. Both are good tires and the clincher version is a little cheaper. Same with Conti 5000 vs. 5000 tubeless.