Do it !!! Its epic fun ... foam tyres work really well under the saloon arches, or if you're really keen then get some innner tubes and stretch over for some tail out rally action ...
Here's a vid from one of our rounds last year running on foams -
http://www.youtube.com/watch?v=3a9Kyf5VKgg
... and if anyone doesn't already know ... WORM have the "Race for cake" meeting on THIS sunday at Hutton village hall in W-S-M. Micro saloons or buggies, drift tyrs supplie but you will need the foams