I have a full set of 13" Slicks I was going to use at Mallala in the hope of getting my times down, but never did before I upgraded by brakes and now need to run 15" rims.
http://www.fsport.com.au/fsport_siteroot/popups/kumho/s700.html
They are ex- Formula Ford and have lots of life left.
They are 180/550R13
Would require a 7" Rim for best I'd say.
These are a cheap way of improving your times. I found second hand semi slicks a vast improvement over performance road tyres, so these should do wonders for budget performance.
$200 for the set.
$125
