The Yok tires are working well for me. If you run stock, I've gotten about 12to 15 runs on a set right now and they are still plenty good to go. But it depends on the track surface and setup you uses. The 139G's do have a thin profile of rubber which means that the tread life may be shorter than some tires. However, many of the better handling tires, like Sorrex, are using this method of thinner rubber to get the tire to hook up better. The thing that has actually impressed me about the 139G's is the way that they wear considering how much traction they have. My tires don't feather at all like my Pit 20's did. And I think the traction of a Sorrex tires goes away with less runs on them. This is just my opinion though.