bmuss, are your rubber tiles similar to these?
http://www.rubbercal.com/Eco_Sport_half_Inch.html
Looks like a couple of them should do it. Do you think 3/4" or even 1" would be feasible (or perhaps an overkill and too high for the wheel to climb on)? I figure the thicker the rubber the better the thermal insulation between the tire and the cold cement floor.
Thx,
Z.