It really depends on the setup:
IF:
weight is greater than 3200lbs and have an automatic
THEN: Radials
IF:
weight is greater than 2900lbs and have an automatic with power adder
THEN: Radials
IF:
weight is less than 3200lbs, have a manual and good gearing
THEN: Slicks
IF:
you are an impatient bastard like myself
THEN: Slicks