In trying to gauge a vehicle’s abilities off-road, the Ramp Travel Index (RTI) is a useful metric. To test the overall axle articulation of a vehicle, one wheel is driven up a ramp – usually with a 20-degree incline – until one or more other wheels loses contact with the ground. The distance traveled up the ramp is measured, divided by the wheelbase, and multiplied by 1,000 to yield a usable RTI score.
In the video above, we get to see a 1916 Ford Model T give it a go – and blow everyone away with its suspension (and chassis) flex.
For reference, Four Wheeler has rated the Jeep Wrangler (JK) Rubicon two-door at 769, according to Hotrod. That means that the two-door off-roader can travel up the ramp a distance that’s about 77 percent of its wheelbase before a wheel starts to lose traction and slip. By comparison, this spry 1916 Ford Model T accomplishes an RTI of 1,030. In the video, you can see it climb up the ramp a total of 103 inches – several inches farther than its 100-inch wheelbase – before a wheel starts to lose contact with the ground.
That’s an amazingly high RTI, and enough to put plenty of dedicated off-roaders to shame. Of course, as we see in the video, it’s not just suspension flex but also frame flex that allows the Ford Model T to stretch so far before lifting a wheel. Nonetheless, the antique car’s impressive axle articulation might provide a valuable clue as to why it was such a sales success to start.