Originally Posted by andrewdoherty

I prefer to use turning radius at the slowest possible speed to communicate this information. It takes into account all the factors involved, whereas simply stating EPA or DR values do not. It also eliminates differences due to radios, servos, steering linkages etc, and keeps me aware of any differences left to right in my steering.

With that said I typically run about a 3.5 foot circle. This is indoors on a low-med grip ozite track. In my opinion you don't want to stray too far from this value as if your circle is too big you won't have enough steering to get through the slower sections as fast as possible and if you make your circle too small you will lose some speed all around as you scrub one or both tires trying to turn a smaller radius than the traction will allow for the speed your car is moving.