What Is Ramp Travel Index (RTI)?
Off-road vehicles twist and flex as their wheels chase uneven ground, and one wheel often lifts off the dirt entirely while the others stay planted. The Ramp Travel Index (RTI) turns that flex into a single number: how far one tire can climb a ramp before a wheel on the opposite corner leaves the ground.
A high RTI usually means a suspension keeps more tires in contact with the trail, which translates into more traction, fewer stuck moments, and a smoother ride over rocks and ruts. That is why RTI shows up on spec sheets for solid-axle trucks and Jeep-style off-roaders, and why it is one of the first numbers serious builders chase when upgrading a suspension.
The RTI Formula
The formula scales the ramp distance by the wheelbase, then multiplies by 1000 so the result reads as a clean, comparable score:
[
RTI = \frac{\text{Distance Traveled Along the Ramp}}{\text{Wheelbase}} \times 1000
]
Both values must be measured in the same length unit before dividing — the calculator above handles the conversion automatically if the ramp distance is entered in centimeters. Multiplying by 1000 is purely cosmetic: it turns a decimal like 0.847 into a much easier-to-read score of 847.
Worked Example
Say a truck's front tire climbs 72 inches up the ramp before the rear tire on the opposite side lifts off the ground, and the truck has an 85-inch wheelbase:
[
RTI = \frac{72}{85} \times 1000 = 847.06
]
An RTI of 847 sits comfortably above the stock-vehicle range, suggesting this particular truck has had some suspension work done — longer-travel shocks, softer springs, or a disconnecting sway bar are common ways builders push scores that high.
What Counts as a Good RTI Score?
| RTI Score | Typical Vehicle | What It Suggests |
|---|---|---|
| Under 400 | Stock sedan or crossover | Minimal suspension articulation; not built for off-roading |
| 400–600 | Stock SUV or truck | Reasonable factory flex for light trail use |
| 600–1000 | Lifted or upgraded suspension | Aftermarket shocks, springs or sway-bar disconnects |
| 1000+ | Dedicated rock crawler | Long-travel suspension purpose-built for extreme articulation |
These ranges are only a guide — ramp angle, tire size and measurement technique all shift the numbers, so RTI is most useful for comparing a single vehicle's before-and-after modifications rather than as an absolute benchmark across brands.
Why Wheelbase, Not Track Width?
It is tempting to assume a wider vehicle would need track width somewhere in the formula too, but the standard RTI calculation never touches it — only ramp distance and wheelbase. That is intentional: wheelbase and ramp distance are both measured along the length of the vehicle, so dividing one by the other produces a clean, dimensionless ratio that is easy to compare across trucks with different wheelbases. Track width instead governs a vehicle's resistance to tipping sideways, a separate stability question the ramp test is not designed to answer.
Quick Recap
- RTI = ramp distance ÷ wheelbase, multiplied by 1000, with both distances in the same unit.
- 847 was the worked-example score — well above the 400–600 stock-vehicle range.
- Track width plays no part in the calculation; RTI isolates suspension articulation along the vehicle's length.
- Use the calculator above to score a ramp run and compare it against factory or modified benchmarks.
If you are evaluating a vehicle's off-road geometry further, the breakover angle calculator is a natural next step.