grip on dusty plywood

[greencactus3]

as a kinda off topic from usfirst, im looking for a tread material, tire material, tire width, size, you get the idea.. that might have the best traction in dusty surfaces, namely plywood. or if thats a bit hard, even on plywood, note not polished wood. and to give an idea this is basically for a sumobot application, but if anyone has any ideas or links to useful sites with this info, please teach me, thanks!. oh and a durable tire material would be nice. by the way, it would be supporting at the minimum 50lbs each. more when pressure is applied, assuming it doesnt slip. so each tire/wheel would be necessary to be rated at least id think 75lbs.
and myself im thinking a soft, gummy tipe of rubber tire would be nice? anyone know where to find any of those? (and since it wont be taking highspeed corners and such, probably wont warm up too well so i think gokart tires are off, unless they make idunno. teach me lol.