heh not often. I have a seperate set for racing. They're called my battle wheels. if you haven't seen em there on the link. GOt whetever wheels I could find to race with hehe, anything I could get my hands on. Got the TSI wheels for 60 bucks and the GSX wheels for 1.50 nope that's not a typo either hehe :P
http://www.imagestation.com/album/?id=4292220497

Anyway check at America's Tire for used tires often. Once in a while I find a great deal. I got w Dunlop W10s excellent tires for 100 bux that I roll with on the streets. I got 2 dunlop qualifier for 50 bucks which were practically brand new but they were 205/40/16 bleh horrible grip, but I give NO mercy to those tires :) Then I just have hella old tires that I wanna blow up, those'll be used for racing too hehe.

Then I have another set of tires for just cruisin and stuff. Heh one day I hope to be able to have a street set of good grippy tires and a good set of racing tires, but getting whatever you can get your hands on worx for now ^_^

Here's the link for my photo album for the event again also, at the end you can see the agony I put the tires through bwahahaah NO MERCY!! I seperated the qualifiers from the rim when I hit the dirt pretty hard, haha man I hate those tires.
http://www.imagestation.com/album/?id=4292210503