Project-JK & Off Road Evolution
JK Ramp Day Meet-n-Greet & RTI Scores

How much flex does my Jeep have and how do I find out? That was the question a lot of the people in the SoCal area were asking me and thanks to the generosity of Off Road Evolution for letting us use their RTI ramp, about two dozen members from JK-Forum.com got to find out last Sunday at our first ever JK Ramp Day Meet-n-Greet.

For those of you who are unfamiliar with the term ‘flex’, it is essentially your Jeep’s ability to articulate its suspension to an exaggerated degree. The more it can articulate (stuff up into the fenders and droop on the opposite side), the longer you can keep all your tires firmly planted on the ground. Of course, the longer you can keep your tires on the ground, the more stable you will be and the more traction you will have.

Now, while there is a specific formula to calculate an RTI score, I have yet to see a definitive method to accurately measure and generate the numbers you need to plug into it. Certainly, there are a myriad of variables that can influence the results one way or another and so for the purposes of our meet-n-greet, Off Road Evolution decided to use a plum bob hung from the center of the axle tube to determine the distance traveled up the ramp. Of course, this was done with the full knowledge that a reading from here would be one that is perpendicular to the ground (as opposed to being perpendicular to the ramp as is normally done) and so all the measurements would be on the short side of things. However, due to the large number of JK’s present, this decision was made to speed things up and keep things equal amongst all the JK’s present. And, if you wanted to get a score that was more reflective of a traditional center of the wheel measurement, that could easily be calculated mathmatically.

Anyway, below are photos and specs of all the JK’s that came to our JK Ramp Day Meet-n-Greet as well as the RTI scores that they received. Just so that it’s clear, Off Road Evolution tried their best to bring everyone straight up the ramp and in the same way one from the next. Unfortunately, not everyone was running the same PSI in their tires but they were all asked to run it at street pressure. To see what they would score with a traditional center of the wheel measurement, we have determined that an additional 10% will give you approximately the answer you are looking for.

How to Calculate RTI


An RTI or Ramp Travel Index score is a tool to help you measure a vehicle’s ability to flex or articulate its suspension. Ramps can vary between 15-30 degrees of angle but most people tend to work off of a 20° ramp. To score a vehicle, you would put one tire on the ramp and drive up it until one of the other three tires starts to lift off the ground. Once that occurs, you back down the vehicle until all the tires are making solid contact with the ground again and then you start to take measurements. To make your calculations, you need to do the following:

1. Measure the distance traveled up the ramp (to center of wheel).

2. Divide that measurement by the length of the vehicles wheelbase (Jeep JK Wrangler Unlimited = 116 inches).

3. Multiply that number by 1000

The final number you get will be your RTI score.

RTI Diagram


b = wheelbase of vehicle

d = distance travelled up ramp before any wheel leaves the ground

r = calculated ramp travel index.

RTI Formula


Special Thanks


I’d like to give special thanks to Off Road Evolution for making their facility and RTI ramp available to the members of JK-Forum.com, for feeding everyone delicious tacos and for helping us make this event as awesome as it was - you guys ROCK!!!

Off Road Evolution

 

   
   
   

JK RTI Ramp Scores - 2 Doors


James90755
JK Color/Model: Red 2dr X
Suspension: Stock
Tire Size: Stock
Distance Traveled: 47 in
Calculated Wheel Lift: 23.5 in

RTI 20° Ramp Score: 723.30

Coldfire
JK Color/Model: Blue 2dr Rubicon
Suspension: 2" OME
Tire Size: 32"
Distance Traveled: 54 in
Calculated Wheel Lift: 27 in

RTI 20° Ramp Score: 831.02

Rangleme
JK Color/Model: Black 2dr X
Suspension: 2.5" Rough Country
Tire Size: 33"
Distance Traveled: 54 in
Calculated Wheel Lift: 27 in

RTI 20° Ramp Score: 831.02

Mud Plz
JK Color/Model: White 2dr X
Suspension: 4" Rancho
Tire Size: 35"
Distance Traveled: 48 in
Calculated Wheel Lift: 24 in

RTI 20° Ramp Score: 738.69

Mikey1989
JK Color/Model: Black 2dr X
Suspension: 4" ProComp
Tire Size: 35"
Distance Traveled: 50 in
Calculated Wheel Lift: 25 in

RTI 20° Ramp Score: 768.96

OffTopic
JK Color/Model: Silver 2dr Sahara
Suspension: 3" FT Ult w/1" spacers
Tire Size: 35"
Distance Traveled: 50.5 in
Calculated Wheel Lift: 25.25 in

RTI 20° Ramp Score: 777.16

Toad
JK Color/Model: Rescue Green 2dr X
Suspension: 4" Rough Country
Tire Size: 35" (aired down)
Distance Traveled: 56 in
Calculated Wheel Lift: 28 in

RTI 20° Ramp Score: 861.80

JK RTI Ramp Scores - 4 Doors


ADX 08
JK Color/Model: Red Rock 4dr X
Suspension: Stock
Tire Size: Stock
Distance Traveled: 49.5 in
Calculated Wheel Lift: 24.75 in

RTI 20° Ramp Score: 623.87

TStrain
JK Color/Model: Black 4dr Rubicon
Suspension: Stock
Tire Size: Stock
Distance Traveled: 50 in
Calculated Wheel Lift: 25 in

RTI 20° Ramp Score: 630.17

Blazer4949
JK Color/Model: White 4dr Rubicon
Suspension: 3" Skyjacker
Tire Size: 33"
Distance Traveled: 44.5 in
Calculated Wheel Lift: 22.25 in

RTI 20° Ramp Score: 560.85

Woods
JK Color/Model: Silver 4dr Rubicon
Suspension: 2"OME
Tire Size: 33"
Distance Traveled: 59 in
Calculated Wheel Lift: 29.5 in

RTI 20° Ramp Score: 743.60

Gryph0n
JK Color/Model: Black 4dr X
Suspension: 2.5" TeraFlex
Tire Size: 33"
Distance Traveled: 60 in
Calculated Wheel Lift: 30 in

RTI 20° Ramp Score: 756.20

Dwikto
JK Color/Model: Yellow 4dr Rubicon
Suspension: 3" BDS
Tire Size: 34"
Distance Traveled: 62 in
Calculated Wheel Lift: 31 in

RTI 20° Ramp Score: 781.41

MrLuminosity
JK Color/Model: Red Rock 4dr X
Suspension: 2" RE
Tire Size: 35"
Distance Traveled: 53 in
Calculated Wheel Lift: 26.5 in

RTI 20° Ramp Score: 667.98

DrDiesel
JK Color/Model: Blue 4dr Rubicon
Suspension: 4" Full Traction w/Fox Shocks
Tire Size: 35"
Distance Traveled: 58 in
Calculated Wheel Lift: 29 in

RTI 20° Ramp Score: 730.99

Overton001
JK Color/Model: Blue 4dr X
Suspension: 4" Skyjacker
Tire Size: 35"
Distance Traveled: 59 in
Calculated Wheel Lift: 29.5 in

RTI 20° Ramp Score: 743.60

BlueJ
JK Color/Model: Blue 4dr X
Suspension: 3" TeraFlex
Tire Size: 35"
Distance Traveled: 61 in
Calculated Wheel Lift: 30.5 in

RTI 20° Ramp Score: 768.80

BEACHN JK
JK Color/Model: Black 4dr X
Suspension: 4" Rancho LA w/Fox Shocks
Tire Size: 37"
Distance Traveled: 52.5 in
Calculated Wheel Lift: 26.25 in

RTI 20° Ramp Score: 661.68

Trail Bud
JK Color/Model: White 4dr Rubicon
Suspension: 4" Full Traction
Tire Size: 37"
Distance Traveled: 53 in
Calculated Wheel Lift: 26.5 in

RTI 20° Ramp Score: 667.98

Rinkrat13
JK Color/Model: Rescue Green 4dr Sahara
Suspension: 4" Rancho LA
Tire Size: 37"
Distance Traveled: 61.5 in
Calculated Wheel Lift: 30.75 in

RTI 20° Ramp Score: 775.11

Ctimrun
JK Color/Model: Blue 4dr Rubicon
Suspension: 4" TeraFlex LA w/EVO Front Coilovers
Tire Size: 37"
Distance Traveled: 68.5 in
Calculated Wheel Lift: 34.25 in

RTI 20° Ramp Score: 863.33

Wayoflife
JK Color/Model: White 4dr Rubicon
Suspension: 4.5" EVO Front Coilovers and Rear EVO Lever w/TeraFlex Short Arms
Tire Size: 37"
Distance Traveled: 74.5 in
Calculated Wheel Lift: 37.25 in

RTI 20° Ramp Score: 938.95

So what do all these numbers mean? I’ll be honest and tell you that by themselves, not a whole lot of anything. An RTI ramp is a great tool that can help you to see what your Jeep is capable of, how much wheel lift it has (basically, how big of a rock you can safely climb) what works, what doesn’t, what could be longer, what needs to be softer, what is rubbing and what you can do about it. When ramped side by side with other similar Jeeps with different builds, you can also learn what components offer up more flex, which ones will limit it and as crazy as it may sound, how most perform more or less the same.

All in all, our first ever JK Ramp Day Meet-n-Greet was more for everyone in our neck of the woods to get to meet new people, get fed outstanding tacos and have a ton of fun. And, if you weren’t able to make it out, I can tell you that we had just that and you missed out big time!!

To see all the pics that we took from the first ever JK Ramp Day Meet-n-Greet, click on the link below:

JK Ramp Day Meet-n-Greet Photo Gallery

 

2 Comments so far

  1. Jeff October 15th, 2008 4:39 pm

    Hey Eddie
    I understand that California has all new testing equipment out there. Out here in Texas we use each others tires to Crawl up on 32’s 35’s 37’s And the 40’s are harder to climb.

  2. Tor Larsen March 30th, 2011 4:31 pm

    ADX 08. Does your X have swaybar disconnect? Does anyone know how high rti score the wrangler sport diesel (european version) have got on an rti ramp?

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