Right now, I don't have a dedicated set of tires for autox, but I would like to since running on the same tires you drive around on sucks (unless you want to burn money by killing a good set of autox tires by driving around town). You described my tirewear pretty well...I have a set of sumitomo htr200s used for daily driving and autox (not much drifting) since about last July I guess. They are close to dead, I'm pretty solidly on the wear indicators but there is still enough tread to not hydroplane everywhere.

I'm getting better suspension soon, including pillowball upper mounts with adjustable camber up front, so wearing down the outside edge shouldn't be as much of an issue as it currently is.