Zerdly

Rolling Resistance Calculator

Rolling resistance is the force needed to keep a machine rolling on a given surface — tyre flex, penetration into the road and internal drag.

100% FreeRuns in your browserBasic
How to use this calculator

Enter Values

Enter your values and press Calculate to see results.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Enter the gross vehicle weight (GVW) — the loaded machine mass in tonnes (empty mass + payload).
  2. Enter the rolling resistance as a percentage of GVW: use ~2% for a firm, well-maintained haul road and 3–4% for soft, rutted or wet surfaces.
  3. Optionally add the ramp grade (%, positive uphill, negative downhill) to also get grade resistance, total resistance and the effective grade the truck's rimpull must overcome.

How it works

Rolling resistance is the force needed to keep a machine rolling on a given surface — tyre flex, penetration into the road and internal drag. It is estimated as a percentage of the machine's weight: force (N) = GVW (t) × 1000 × 9.81 × (RR% ÷ 100). A common rule of thumb is about 10 N per tonne of GVW for each 1% of rolling resistance. The result is shown in kilonewtons and as newtons per tonne so it scales to any truck size.

When a ramp grade is entered, grade resistance = weight × (grade% ÷ 100) is added (using the small-angle approximation tan ≈ sin, accurate for typical haul-road grades under about 10%). The sum, total resistance, is the rimpull force the truck must produce to hold steady speed — compare it against the manufacturer's rimpull/retard chart. This is a steady-speed force estimate and does not account for acceleration, traction limits or gearing.

Worked example

240 t haul truck on a 3% road up an 8% ramp. A loaded rigid dump truck has a GVW of 240 t on a haul road with 3% rolling resistance, climbing an 8% ramp. Weight = 240 × 1000 × 9.81 = 2,354,400 N. Rolling resistance force = 2,354,400 × 0.03 = 70,632 N ≈ 70.6 kN (294.3 N per tonne). Grade resistance = 2,354,400 × 0.08 = 188.4 kN, so total resistance = 259.0 kN at an effective 11% grade — that is the rimpull the truck must produce to hold speed on the ramp.

Common mistakes

  • Using empty machine mass instead of GVW. Rolling resistance scales with the loaded weight, so a truck at full payload can have double the empty-vehicle resistance — always use gross (loaded) mass.
  • Entering rolling resistance in kg or N instead of a percentage of GVW. This field is the RR coefficient as a percent (typically 2–4%), not a force.
  • Confusing rolling resistance with grade resistance. Rolling resistance comes from the road surface and tyres; grade resistance comes from the slope. They add together to give the total resistance the truck must overcome — don't report one as if it were the total.

Frequently asked questions

What is a typical rolling resistance percentage for a mine haul road?

About 2% on a firm, dry, well-maintained and well-drained haul road. It rises to 3–4% on soft, muddy, rutted, sandy or poorly maintained surfaces, and can exceed 5–8% in very poor conditions. Good haul-road maintenance directly reduces fuel burn and cycle time because rolling resistance is a force every truck fights on every metre travelled.

How does rolling resistance relate to grade?

Both are expressed as a percentage of the machine's weight and simply add. If a road has 3% rolling resistance and the ramp is at 8%, the truck feels an effective 11% grade — total resistance = weight × 11%. That total is the rimpull the engine and drivetrain must supply to hold speed. Downhill, a negative grade subtracts, and the truck's retarder/brakes must absorb the surplus.

Does this account for engine power, gearing or traction?

No. This tool gives the steady-speed resistance force only. To find achievable speed you divide usable rimpull power by this force, and real performance is also capped by available traction (tyre grip) and the gear the truck is in. Always cross-check against the OEM rimpull and retard/braking charts for the specific machine.

Related tools

Explore more in Mining, Quarry, Earthworks, Drill & Blast.

Tip: Enter any known values to calculate the remaining results.

All calculations run in your browser. Your inputs are never saved or transmitted.