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Automotive Calculators

Wheel Travel Calculator

2026-09-27 6 min

Total wheel travel and RTI-style index from droop, bump and wheelbase.

Total Travel
10.00 in
RTI-Style Index
83.3 pts
Travel/wheelbase x 1000

Calculator

Droop Travel(in) Help
in

Extension below ride height

Bump Travel(in) Help
in

Compression above ride height

Wheelbase(in)
in
Results update live as you type

Live statistics

Total Travel

10.00 in

RTI-Style Index

83.3 pts

Travel/wheelbase x 1000

Results

Optimal

Total Travel

10.00in

RTI-Style Index

83.3pts

Travel/wheelbase x 1000

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

10Total Travel
83.3RTI-Style Index

Total Travel vs. Droop Travel

Total Travel

10in
024

Formula

Usable stroke sums both directions; normalizing by wheelbase ranks flex across rig sizes.

Total = droop + bump; index = total / wheelbase x 1000

Variables

SymbolNameUnitDescription
TTotal travelinDroop plus bump stroke

Explanation

5 + 5 = 10 in total; 10/120 x 1000 = 83.3 pts — a mild stock-flex score.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

Droop Travel:5 in
Bump Travel:5 in
Wheelbase:120 in
Result: 3 inputs ready
Step 2

Apply the formula.

Total = droop + bump; index = total / wheelbase x 1000
Result: Primary result = 10.00 in
Step 3

Read every derived output.

Total Travel:10.00 in
RTI-Style Index:83.3 pts
Result: Total Travel = 10.00 in
Final Answer
10.00

Worked Examples

See how the calculator works with different scenarios.

Scenario

Stock IFS corner on the rack.

Inputs

Droop:5 in
Bump:5 in
Wheelbase:120 in

Calculation

Total 10 in; 10/120 x 1000 = 83.3

Result

10 in travel, 83.3 pts.

Interpretation

Long-travel kits double this number.

Understanding Your Result

Your Result: Total Travel: 10.00 in

Typical range: Stock IFS 8-10 in; long-travel 12-16 in; solid-axle crawlers 20 in+.

What This Means

Vertical wheel stroke available to follow terrain.

Why It Matters

Travel keeps tires planted over uneven ground — droop especially holds contact in holes.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

  • •Double-check units on every input before trusting the result
  • •Compare against the worked example below to sanity-check magnitude
  • •Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Wheel travel is the sum of upward bump stroke and downward droop from ride height.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

  1. Fill to first click at the same pump, record the odometer (Tank 0).
  2. Drive normally for 2–3 tanks; always refill to first click at the same pump.
  3. MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
  4. Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
  5. Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

  • •Droop keeps tires down in holes
  • •Bump stops protect the shocks
  • •Flex one corner, measure at the hub

Common Mistakes

Mixing units (inches with mm, psi with kPa)
Convert every input to the unit shown on its field before calculating.
Trusting a single output blindly
Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.
Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.
No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

What is RTI?
Ramp Travel Index: distance up a 20-degree ramp divided by wheelbase, x 1000. This index approximates it from vertical travel.
Droop vs bump — which matters more?
Droop (extension) keeps tires on the ground through dips; bump (compression) absorbs hits. Crawlers bias droop, jumpers bias bump.

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG
Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km
Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe
Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE
Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance
Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag
Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling
Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II
On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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