The R version has a thinner chassis and top deck, soft arms, 4 degree caster, and i believe it comes with a spool. So this car is set up for rubber. The F version had thick chassis and top deck, hard arms, 6 degree caster.
So the R is ideal for rubber. I just picked up both version. I ordered a oneway for my rubber car because that works very well for 17.5 at my local track.
Awesomatixusa - Side Piece Racing - LRP - Sweep Racing Tires - Mike L Designs - TQ Wires - Crispy Critters Raceway