A vehicles RTI or ramp travel index is a measurement of a vehicles suspension (and frame) flexibility. In many situations offroad a vehicles flexibility may be the determining factor of whether or not it can get over an obstacle.
If a vehicles suspension is too stiff this may cause a tire or two to be lifted, loosing contact and traction, especially apparent in vehicles with open differentials.
While locking differentials will help to maintain forward momentum when a wheel is off the ground, good flexibility will help to keep the wheels on the ground and more able to conform to the terrain.
RTI Calculator will help you determine your RTI score in a fast and easy way.
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