First off I work in a hangar there are bolts, nuts, metal shavings, pebbles, extensions, rivets, zip ties, anything you need for me can imagine on the floor I bought these to replace my original wheels on my tool box that drives around the hangar every day.They are over the top in terms of weight capacity but I bought them for the rubber material so they not constantly snagging on nuts and rivets that might get stuck in my old plastic wheels, ironically I almost need a horn on my box because it rolls so quietly now and yes they have, there is a slight chemical smell (new rubber), when you open the bag for the first time, I think it took a full 30 seconds for the smell to go away, at least for me and I think for everyone n who really need heavy skates or rubber/tread skates will agree they cost $20 per wheel.