Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.

Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.

Automotive Calculators

Tire Slip Ratio Calculator

2026-09-27 6 min

Longitudinal slip ratio and linear-region traction estimate from wheel speed vs vehicle speed.

Slip Ratio: 9.1 %
Traction Index: 1364 lb; Linear-region proxy (slip x 150)

Calculator

Wheel Speed(mph) Help

mph

Tire surface speed equivalent

Vehicle Speed(mph)

mph

Results update live as you type

Live statistics

Slip Ratio

9.1 %

Traction Index

1364 lb

Linear-region proxy (slip x 150)

Results

Optimal

Slip Ratio

9.1%

Traction Index

1364lb

Linear-region proxy (slip x 150)

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

Visualizations

Results overview

9.1Slip Ratio

1,364Traction Index

Slip Ratio vs. Wheel Speed

Slip Ratio

9.1%

-2030

Formula

Driven-wheel overspeed normalized by road speed; small slip builds traction linearly.

Slip = (wheel - vehicle) / vehicle x 100

Alternative Form

Traction proxy = slip% x 150 lb (linear region)

Variables

Symbol	Name	Unit	Description
w	Wheel speed	mph	Tire surface equivalent
v	Vehicle speed	mph	True ground speed

Explanation

Peak straight-line grip lives near 8-12% slip — spinning far past it just makes smoke and heat.

Step-by-Step Calculation

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

Step 1

Record the inputs.

Wheel Speed:60 mph

Vehicle Speed:55 mph

Result: 2 inputs ready

Step 2

Apply the formula.

Slip = (wheel - vehicle) / vehicle x 100

Result: Primary result = 9.1 %

Step 3

Read every derived output.

Slip Ratio:9.1 %

Traction Index:1364 lb

Result: Slip Ratio = 9.1 %

Final Answer

9.1

Worked Examples

See how the calculator works with different scenarios.

Scenario

Hard launch on street tires.

Inputs

Wheel:60 mph

Vehicle:55 mph

Calculation

(5/55) x 100 = 9.1%; index 1,364 lb

Result

9.1% slip — right at the traction peak.

Interpretation

Hold it there; more throttle only adds spin.

Understanding Your Result

Your Result: Slip Ratio: 9.1 %

What This Means

How much the driven tire overspeeds the road under power.

Why It Matters

Launch and traction control target the slip peak, not zero spin.

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

Driven tires must spin slightly faster than the road to pull.

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)

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

Practical Tips

•Peak grip is 8-12% slip on most tires
•Negative slip means braking lockup zone
•Log wheel vs GPS speed to find your peak

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.

Is some wheelspin faster?

Yes — peak longitudinal force needs ~10% slip; dead-hook with zero slip leaves grip unused.

Is the traction force exact?

No — a documented linear-region proxy. Real curves need tire test data.

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Related Guides

Deepen your understanding with these educational resources.

Automotive Guides

Build planning, measurement protocol and validation how-tos

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.

EPA — FuelEconomy.gov DOE — Fuel-Efficient Driving Tips NHTSA — Driving Safety & Efficiency SAE International — Fuel Economy Standards Consumer Reports — MPG Truth IRS — Standard Mileage Rates

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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Page Information

Last Updated:

2026-09-27

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.