If you've never bought a pair of Chucks before, go to an actual shoe store that sells the things to try on and fit. Sizing will be slightly off from what you're used to, and getting them too big will cause them to wear and fail sooner. I average Men's US 11/11.5 in most brands. In Chucks, I'm a 10.5. Be forewarned if you have wide feet or need arch support, they won't be super comfortable. Chucks are divisive, they'll ether be the most comfortable shoes you've ever worn or you'll hate 'em.
Sometimes the edge of the sole will blow out around the outer front/side of the shoe before the soles are completely worn. It's a defect I've found that hits about 15% of the shoes, but is also hastened if you don't size the shoe to fit tight like a glove and your foot slides around inside. Otherwise, a pair of high top leather Chucks last me on average around 24-30 months. I've gone through six pair (I think?) over the past eleven years since I started wearing them, and they started lasting longer after I sized down for a good fit.