Purchased two (2) sets of these, a total of four (4) covers, to protect my vehicles 265/70R17 (31.6" diameter) tires. Based on manufacturers description I should have been able to purchase ADCO 3952 which are good for up to 32" tires. I erred on the side of caution and instead purchased 3951 which are stated to be for 33"-35" tires. I'm glad I did as these are a snug fit without being too tight or difficult to install. The smaller size would probably have difficult to install.My only dislike with these covers are the bungee cord fastening system. I have a set of Camco covers on my trailer tires that uses a strap with quick click connector on the backside of the cover. It's not that the bungee cord is bad but it is more cumbersome to thread through grommets than clicking a buckle together.