Superhero I did that last year. I got stuck after buying my 17 inch wheels not being able to afford a set of tires for them and a dedicated set of wheels tires for racing. I ended up putting Advan (yokohama) AO32R's on them. Later in the season I did get a set of all seasons to run on the street but it was so much fun having the R-comps I just left them. This year I have Kumho MX's on stock 16 inch wheels. They are great on the street, quite sticky, good rain performance...a little weak in the sidewall but not bad at all when pressures are high. I auto-x'ed once in the rain with them and they were excellent. I will probably do one or two more races this year.
Keep in mind, Boundary bay (where almost ALL of Vancouver's auto-x's are) has a surface that is very hard on tires. If you do three dry events with 6+ runs per event you will chew up the tires pretty well.
I would recommend getting a set of used tires for racing, and just chew the rest of them up in a few races. Keep your good set of tires for the street in good condition.