wheel cover socket wrench

I got most of my larger sockets at one of the auto stores. I prefer the heavy black impact sockets in 1/2 inch over the regular shiny ones. Your wheel cover "lugs" as you call them have a slightly larger real lug nut under them holding the wheel on. If I remember correctly I needed both 31 and 33 mm on my 19.5 wheels. Also the torque on the workhorse chassis wheel lug nuts (not cover retainers) is over 400ft/lbs. TMI but good info if you need to go there.