I have autocrossed Formula Fords on slicks since 1986. I have given my old slicks to other autocrossers to try, and many have liked them. I have run 13" rims from 5.5" wide to 11" wide.

I would suggest to go with a softer compound, not a harder compound. The softer compound gives better grip while cold, and one does not have the chance to get tires warm at autocrosses. The harder compound would slip much easier, thus wearing out much faster. I learned this at a SOLO I at Sebring in 1988.

Also, I only run Hoosiers. They are a far superior tire for autocrossing.

You could probably get away with the 22X9X13 tires that are rear tires for S2000, FC, DSR, etc. There was a racer in CFR that ran a Chevette in GP. He used the 22X9X13 FC rear tires on all 4 corners of the car, and it handled well. Hoosier does make slicks for sedans. http://www.hoosierracingtire.com/rrtire.htm

If you can get away to Roebling Road on the July 4 weekend, there is a double national road race that weekend. I have gone there in the past to dumpster dive for take offs. I have left with as many as 40 tires at that event. Talking nicely to the tire guys, and asking them which tires are the throw aways should lead you to the tires that are being disposed of. Free ain't bad!!!!!

3 years ago I tried a set of Avon tires. I really liked them. It turned out that the set I got were experemintal tries (made for qualifying at the June Sprints at Road America, with the plies being made of kevlar. They were very light tires, and handled well.

Many top National road races feel that tires lose their edge with 4 heat cycles, so those with a large budget put 3 heat cycles on them and then throw them out.

If you do get slicks, keep the deflated and sealed in dark trash bags away from UV light and any source of ozone. They will stay soft much longer by treating them this way.