[AGAV13]

I want to get a dedicated set of track/autoX wheels and tires. I'm going to say this up front just to get it out of the way, I don't have much knowledge about wheel and tire sizing and have done research but do not fully understand what I am reading. So please don't just say "Search," I am looking for some good honest feedback so I can put more effort into researching my options. I do however know that I want a square set up. As of now my 135is is stock with the hope of doing suspension/springs and fender rolling some day. What would be the best sizing (size and width) for a dedicated track and autoX set up? Any feedback is appreciated, thank you.