I'm gonna echo what has already been said. Buying new tires isn't that big of a deal. That's just the cost of maintaining a bike. If you ride a lot, you're going to have to replace your tires frequently regardless of whether or not you skid. Skidding definitely doesn't help, though. I ride brakeless and don't skid very much at all. In fact, I don't think I've skidded in at least a week or so.