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Land Rover Ramp Travel Index Calculation and Table

The original ramp is a metal structure with a 20-degree slope that is used to measure a vehicle's ability to conform to the terrain. 

Suspension travel and chassis flex are two important qualities needed to traverse uneven, rutted terrain, and the ramp is a fair, controllable, and repeatable way to measure them. 

There's no room for driver error or luck to influence the outcome; a number achieved on the ramp is directly comparable between different vehicles, any day, anywhere in the world.

Ramp Travel Index is an accurate way of telling how far up the 20-degree ramp a vehicle can go, while still keeping all four tyres in contact with the surface. To some extent, mathematical manipulations are necessary; it would be unfair to ask a short-wheelbase vehicle to crawl as far up the ramp as one with a long wheelbase. Therefore, whatever number of inches a vehicle can muster before it runs out of suspension travel (and chassis flex) is divided by its wheelbase. (This way, a 130 can indeed compete with a 90. We multiply that number by 1,000 to get kind of a workable value.

For example, if a 110-inch-wheelbase vehicle goes 52 inches up the ramp, its RTI number would be 472 ([52 110] x 1,000). Obviously, a higher RTI number translates into better conformability to the terrain. A perfect score would be 1,000, indicating that the vehicle can go as far up the ramp as its wheelbase is long without lifting a tyre. No standard vehicle has reached 1000 but Range Rovers come close. A few modified machines have indeed reached the perfect score and beyond.

Simple as it is, the ramp tells a great deal about a vehicle's capabilities on the trail. It's also quite useful for evaluating suspension kits, checking shock lengths, finding interference points and other things that may only occur at the extremes of wheel travel.

How do you cheat? You can't, but you can be sloppy. Measuring accuracy is important. Also, differences in tyre pressure will result in minor gains travelling up the ramp. These can result in slightly different scores for seemingly identical vehicles. Accuracy can be enhanced by testing with all four tyres inflated to exact recommended specifications.

So how do you improve your RTI ?

Generally, articulation is a function of your spring rate, shock absorber travel and suspension geometry.
Newer vehicles like Later Range Rovers, Discoveries and Defenders, have various safety aids fitted such as Anti-Roll bars or Anti-Sway bars. 

The basic function of these bars is to male wheels on the same axle follow each other up or down - if the left wheel goes up into the wheel arch it will tend to lift the right wheel as well, this in in contradiction to articulation.

You can temporarily remove them for off-roading, but they must be reconnected when returning to high speed driving.

Here are some typical values of RTI on a 20 Degree ramp.

Vehicle RTI Vehicle RTI
'96 Jeep Wrangler:  357 '93 Isuzu Trooper RS 2-dr.: 529      
95 GMC Jimmy 4-dr. 371 '97 Jeep Wrangler: 532
'92 Suzuki Vitara 4-dr. 379   '94 Dodge Ram 1500: 556    
'93 AM General Hummer: 385 '94 Land Rover Defender 90: 580
'93 Isuzu Rodeo LS:  435   '95 Land Rover Discovery  588  
'93 Jeep Grand Cherokee: 439 '93 Range Rover County LWB  588
'93 Toyota 4Runner: 441   '93 Toyota Land Cruiser:    593  
'94 Ford Explorer Limited  443 '96 Range Rover 4.0SE: 600
'96 Nissan Pathfinder: 466   '92 Range Rover Classic: 670   
'96 Kia Sportage:  471 '80 Range Rover 2dr Classic  730

 

We have made a pre-calculated table that you can use to calculate your own RTI.
All you need to do is drive your vehicle up any ramp or obstacle (Provided the 3 other wheels are on level ground) and measure the height of the wheel tread off the ground. 
You can also try hacking up one wheel in your garage, there will be a bit of error is this since the contact area of the tyre with the would be ground must be estimated.

This will then be the entry into the left hand column of the table below. Find the vertical column for your Land Rover, read off the RTI.
 

Ramp Travel Index Chart for all ramp angles normalised to the 20 Degree International Standard

Height

Converted to

Travel on a

20 Deg RTI

20 Deg RTI

20 Deg RTI

20 Deg RTI

20 Deg RTI

20 Deg RTI

in cm

Inches

20 Deg Ramp

for 88"

for 92.5 (D90)

for 100"

for 109"

for 110"

for 127"

20

7.87

23.02

261.61

248.89

230.22

211.21

209.29

181.28

22

8.66

25.32

287.78

273.78

253.24

232.33

230.22

199.40

24

9.45

27.63

313.94

298.66

276.26

253.45

251.15

217.53

26

10.24

29.93

340.10

323.55

299.29

274.58

272.08

235.66

28

11.02

32.23

366.26

348.44

322.31

295.70

293.01

253.79

30

11.81

34.53

392.42

373.33

345.33

316.82

313.94

271.91

32

12.60

36.84

418.58

398.22

368.35

337.94

334.87

290.04

34

13.39

39.14

444.74

423.11

391.38

359.06

355.80

308.17

36

14.17

41.44

470.91

448.00

414.40

380.18

376.72

326.30

38

14.96

43.74

497.07

472.89

437.42

401.30

397.65

344.42

40

15.75

46.04

523.23

497.77

460.44

422.42

418.58

362.55

42

16.54

48.35

549.39

522.66

483.46

443.54

439.51

380.68

44

17.32

50.65

575.55

547.55

506.49

464.67

460.44

398.81

46

18.11

52.95

601.71

572.44

529.51

485.79

481.37

416.94

48

18.90

55.25

627.87

597.33

552.53

506.91

502.30

435.06

50

19.69

57.56

654.04

622.22

575.55

528.03

523.23

453.19

52

20.47

59.86

680.20

647.11

598.57

549.15

544.16

471.32

54

21.26

62.16

706.36

672.00

621.60

570.27

565.09

489.45

56

22.05

64.46

732.52

696.88

644.62

591.39

586.02

507.57

58

22.83

66.76

758.68

721.77

667.64

612.51

606.95

525.70

60

23.62

69.07

784.84

746.66

690.66

633.64

627.87

543.83

62

24.41

71.37

811.01

771.55

713.68

654.76

648.80

561.96

64

25.20

73.67

837.17

796.44

736.71

675.88

669.73

580.08

66

25.98

75.97

863.33

821.33

759.73

697.00

690.66

598.21

68

26.77

78.28

889.49

846.22

782.75

718.12

711.59

616.34

70

27.56

80.58

915.65

871.11

805.77

739.24

732.52

634.47

72

28.35

82.88

941.81

895.99

828.79

760.36

753.45

652.59

74

29.13

85.18

967.97

920.88

851.82

781.48

774.38

670.72

76

29.92

87.48

994.14

945.77

874.84

802.60

795.31

688.85

78

30.71

89.79

1020.30

970.66

897.86

823.73

816.24

706.98

80

31.50

92.09

1046.46

995.55

920.88

844.85

837.17

725.10

82

32.28

94.39

1072.62

1020.44

943.91

865.97

858.10

743.23

84

33.07

96.69

1098.78

1045.33

966.93

887.09

879.02

761.36

86

33.86

98.99

1124.94

1070.22

989.95

908.21

899.95

779.49

88

34.65

101.30

1151.10

1095.10

1012.97

929.33

920.88

797.62

90

35.43

103.60

1177.27

1119.99

1035.99

950.45

941.81

815.74

92

36.22

105.90

1203.43

1144.88

1059.02

971.57

962.74

833.87

94

37.01

108.20

1229.59

1169.77

1082.04

992.70

983.67

852.00

96

37.80

110.51

1255.75

1194.66

1105.06

1013.82

1004.60

870.13

98

38.58

112.81

1281.91

1219.55

1128.08

1034.94

1025.53

888.25

100

39.37

115.11

1308.07

1244.44

1151.10

1056.06

1046.46

906.38

 

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