RTI

Ramp travel index measures how much vertical suspension movement an off-road vehicle can achieve before hitting its physical limits. It combines suspension travel distance with the angles at which the vehicle meets the terrain, expressed as a single number that reflects real-world climbing and obstacle-crossing ability. RTI matters because a vehicle with long suspension travel can still get stuck if its frame or bumpers contact the ground first.

The calculation involves measuring the suspension's maximum up-travel and down-travel at different axles, then accounting for the vehicle's wheelbase, track width, and breakover angle. A longer wheelbase reduces RTI even with identical suspension components, because the vehicle's center sags into terrain more easily. Breakover angle, the peak of the triangle formed by front tire contact, highest body point, and rear tire contact, is the limiting factor for many stock vehicles.

RTI is expressed as a simple number, typically between 400 and 1000 for production vehicles, where higher indicates better off-road capability. Vehicles modified with longer-travel suspensions, smaller tires (which lowers the vehicle), raised frames, or shortened overhangs improve their RTI. The metric is most useful for comparing vehicles with similar construction; a short-wheelbase purpose-built off-roader and a long-wheelbase truck with identical suspension travel will have very different RTI values.

The term emerged from rock-crawling and extreme off-road communities in the early 2000s as a way to objectively rank vehicles beyond simple suspension measurement. It has become a standard specification in off-road vehicle marketing and engineering, particularly for vehicles designed to navigate steep terrain, rocky obstacles, and rough backcountry trails. RTI reflects the compromise between comfort (which favors longer wheelbase) and obstacle-clearing ability (which favors shorter wheelbase and higher clearance).