RTI Calculator

R T I - C A L C U L A T O R

Driver/Plate:
SMS Phone:
Direction:()FWD    REV()
Side:()LEFT RIGHT()
Wheelbase:"
Wheelheight:"
[clear form]

Fomula used here: RTI = WH \ WB * 2924
This yields RTI for a 20° ramp and is the standard.




[PRIVACY]
None of this form data is stored anywhere.


Some Discussion…

What is RTI?
Ramp Travel Index is a calculated value that is frequently used to quantify a vehicle’s suspension articulation.

How is RTI Scored?
—MEASURING for RTI:
First the vehicle is measured. The Wheebase(wb) is measured and then the vehicle is carefully driven up the ramp until any opposite tire (Other side or same side rear) no longer touches or has grip. If any tire lifts from the ground, the vehicle is carefully backed down the ramp until three(3) tires are just touching. This is the Scoring Position.
Once in the Scoring Position, and depending on the calculation method/formula, either:
Wheelheight(wh) is measured from the ground to the bottom of the lifted tire. /or/
Distance Traveled(dt) is measured from the start of the ramp to a point perpendicular with the ramp and intersecting the lifted tire’s hub.

–CALCULATING RTI :
There are two methods for calculating RTI score.
» Formula for Method_WH: RTI = ( wh / wb * 2924 )
++Yields a standardized RTI regardless of ramp angle used.
— Can be more difficult to measure accurately on ramps for formal competitions
» Formula for Method_DT: RTIθ = ( dt / wb * 1000 )
++Simple to remember
++More accurate measurements if attention is paid to the dt measurement.
— Can give misleading scores for ramps that are not 20°

Some Terms:
Distance Traveled(dt) : Is the distance, in inches, that the lifted tire travels up the ramp
Ramp Angle(ra) : is the angle from the ground to the drivable plane of the ramp. The standard Ramp Angle is 20°. However, it’s not uncommon for some ramps to be closer to 30°.
Scoring Position : Lifted tire is on the RTI ramp and three other tires are all touching the ground.
Wheelbase(wb) : is the distance, in inches, between the front tires and rear tires. And is typically measured hub to hub or leading edge to leading edge.
WheelHeight(wh) : Is the distance, in inches, from the ground to the bottom of the lifted wheel.

Why might I care About Ramp Angle?
Imagine a Lamborghini Countache on a 1° ramp with its 96.4″wb.
All it has to do is drive 96 inches up that 1° ramp to post an RTI score of 1000.
That’s an extreme example to make the point that that ramp angles of 20°-30° help to separate articulation differences in extreme cases. There are rock buggies that score over 1000 on a 20° ramp but could not make that same score on a 30° ramp.