What is the cut off for weight to determine wither to use an aluminum of a steel flywheel? My car with me in it and a half tank of gas weighs in at 3926#. I have run both types of flywheels. The difference in ET and MPH with my set up is minimal. My car is mostly street driven. Street manners with the steel wheel seems better. The aluminum wheel weighs in at around 20# . The steel wheels is around 33#'s.