Reaction times. The smaller the front tire the quicker your reaction times will be. If you are racing on a .400 Pro Tree you generally need all you can get.

FWIW my big tire car has a 33" rear tire and I run a 26" tire on a pro tree. But it is a tube chassis car, which is a different animal than what you are building.

"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"