Buy some big tires and do some testing on the surfaces in similar conditions that you will compete on I have two sets of tires mounted up on similar rims,(same brand and style, one set of ten inch and one set of twelve inch ) both are the same size M/T ET Street DOT tires, one set is the radials ET Streets and the other stet is the bias ply ET Street Tires, the bias plys work better on the street and the radails are faster on a good track My car runs low tens on pump gas corked up on motor only, 3450 lbs with me in it