My RTI (ramp travel index)
Took the truck over to some friends of mine at work and they lifted the front tire off the ground (using a forklift) until my rear was just clear, then lowered it back down to make the rear make contact again.
I had just over 30 inches of travel giving me a calculated RTI of about 700. I'll take that for a first pass at building the truck.
Used a 20 degree ramp equivalent, and 126" wheelbase for the calculations.