Rolling Resistance Calculator
Work out the force that holds a car, bike, truck, or rail vehicle back, using 15 tire and surface presets or your own rolling resistance coefficient.
Rolling resistance is a force, not a speed limit
It is the steady backwards force created where a wheel meets a surface, mostly from the rubber flexing and springing back. Its size depends on how hard the wheel presses down and how lossy the wheel–surface pairing is.
Enter a vehicle mass and pick how you want the coefficient determined. Add a speed to also see the power drain and the energy spent every 100 km.
How to use the rolling resistance calculator
- Pick how the coefficient is found: a ready-made wheel-and-surface preset, a number you already have, a wheel radius with its friction arm, or an estimate from tire pressure and speed.
- Enter the vehicle mass: kilograms, metric tons, or pounds, including everything on board.
- Add a speed if you want power: the force alone answers "how hard is it held back", the speed turns that into watts.
- Calculate: read the force, the coefficient applied, the normal force, and the energy spent per 100 km.
- Compare surfaces: the grid re-runs the same vehicle across all fifteen presets so you can see what the road matters.
Formula: how rolling resistance is calculated
A rolling resistance calculator determines the force needed to overcome tire or wheel resistance on a surface. Calculate rolling resistance with Fr = Cr × N, where Cr is the rolling resistance coefficient and N is the normal force. On level ground, N = mg, so Fr = Crmg.
In other words, the whole calculation collapses into mass, gravity, and a single number describing the wheel–surface pairing. That coefficient carries all the physics of what the tire and the road do to each other; everything else is arithmetic.
For example, a 1,500 kg car rolling on asphalt with a coefficient of 0.013 pushes down with about 14,710 N and is held back by roughly 191 N. At 100 km/h that costs around 5.3 kW — before any air resistance is counted.
F = Crr × N = Crr × m × g
Crr = b / r
P = F × v
The second form is useful when a source gives the coefficient as a length rather than a pure number. That length, often written b, is the forward offset of the contact patch caused by deformation, and dividing it by the wheel radius returns the dimensionless coefficient. It explains why a large wheel rolls more easily than a small one over the same ground.
On a slope the normal force shrinks to m × g × cos θ while gravity adds its own component along the road. This calculator assumes level ground, which is the standard assumption behind published coefficient tables.
Coefficient reference: The Engineering ToolBox tabulates rolling friction and rolling resistance values for common wheel and surface pairs, in both dimensionless and length form.
Rolling resistance coefficients by wheel and surface
These are the fifteen presets built into the calculator. The last column shows the force on a 1,500 kg vehicle at standard Earth gravity, so the spread between a rail wheel and a tire in sand is easy to see.
| Wheel and surface | Category | Crr used | Typical range | Force on 1,500 kg |
|---|
What actually causes rolling resistance?
Very little of it is sliding friction. Most of the loss happens inside the tire itself: rubber is viscoelastic, so the part squashed flat under the load does not give back all the energy when it springs out again. The difference leaves as heat, which is why tires warm up on a long drive.
| Source of loss | What is happening | What changes it |
|---|---|---|
| Hysteresis in the tire | Rubber deforms and rebounds imperfectly, converting motion into heat. | Compound, casing construction, tread depth, temperature, inflation pressure. |
| Deformation of the surface | Soft ground sinks under the wheel, so the vehicle climbs out of its own rut. | Sand, mud, and gravel dominate here; concrete barely deforms at all. |
| Micro-slip in the contact patch | Parts of the footprint scrub sideways and lengthwise as the tire rolls. | Tread pattern, camber, toe alignment, cornering loads. |
| Bearings and driveline drag | Not strictly rolling resistance, but it shows up in coast-down tests. | Lubrication, seals, brake drag, wheel bearing condition. |
Why the coefficient is not one fixed number: the same tire can measure differently depending on load, pressure, temperature, speed, and the test standard used. Laboratory methods run a tire against a large drum under controlled conditions precisely so results can be compared, which is also why published values carry ranges rather than exact figures.
Rolling resistance versus aerodynamic drag
Rolling resistance is roughly constant with speed, so the power it costs rises in a straight line. Drag rises with the square of speed and its power demand with the cube. The two curves cross somewhere in the middle of normal driving, and where they cross decides what is worth spending money on.
| Situation | Which dominates | What that means in practice |
|---|---|---|
| City driving, stop-start | Rolling resistance and inertia | Tire choice and vehicle mass matter more than body shape. |
| Highway cruising | Aerodynamic drag | A roof box costs far more fuel than a slightly stickier tire. |
| Cycling at 20 km/h | Comparable | Tire and tube choice is a genuine, cheap speed gain. |
| Cycling above 30 km/h | Aerodynamic drag | Position and clothing outweigh anything the tires can do. |
| Freight rail | Rolling resistance is tiny | Steel on steel is why a locomotive can pull thousands of tons. |
Before buying low rolling resistance tires: check the cheap fixes first. Correct inflation pressure, good alignment, and less dead weight in the boot all reduce the same force, cost nothing, and do not trade away wet grip.
Energy breakdown: the U.S. Department of Energy's Where the Energy Goes pages set out how a car's fuel energy divides between the engine, driveline, aerodynamic drag, and rolling resistance, and note that a 5–7% cut in rolling resistance buys roughly 1% better fuel efficiency.
Two quick examples
1,500 kg car on asphalt
0.013 × 1,500 × 9.80665 = 191 N. At 100 km/h that is about 5.3 kW, or roughly 5.3 kWh of work for every 100 km travelled.
Rider plus bike, 85 kg, on asphalt
0.004 × 85 × 9.80665 = 3.3 N. At 20 km/h that is only about 19 W — small, but a real share of what a casual cyclist produces.
Interesting fact: rolling resistance matters more in an electric car
The U.S. Department of Energy's Alternative Fuels Data Center reports that a conventionally fuelled passenger vehicle spends roughly 4%–7% of its fuel overcoming tire rolling resistance, while an all-electric passenger vehicle can spend about 25% of its energy on the very same force — and heavy trucks 30%–33%. The gap is not because EV tires are worse. It is because an electric drivetrain wastes so little energy elsewhere that rolling resistance becomes a much larger slice of a much smaller pie, which is why range-focused tires are now a serious engineering target. The same source estimates that cutting rolling resistance by 10% improves fuel economy by roughly 3% for light- and heavy-duty vehicles alike.
How to interpret the results
Presets are representative, not measured
Each preset uses one value from a published range. Two tires on the same road can differ by a third or more, so treat the output as an estimate with a band around it.
This is level-ground, steady-speed only
Gradients, acceleration, cornering, wind, and braking are all separate forces. Rolling resistance is only one line in the total power budget.
Wheel size affects it, tire width less so
A larger radius lowers the coefficient for the same deformation. Width mostly changes the shape of the contact patch rather than its area, which is why wider tires are not automatically slower.
Frequently Asked Questions
What is the rolling resistance formula?
The rolling resistance formula is F = Crr × N, where Crr is the dimensionless rolling resistance coefficient and N is the normal force — the load pressing the wheel down onto the surface. On level ground that load is simply the vehicle's weight, mass × gravity, so the working version this calculator applies is F = Crr × m × g. If your source gives the coefficient as a length b instead, divide it by the wheel radius first. What comes out is a resistance force in newtons that pushes back for as long as the wheels keep turning.
How do I calculate rolling resistance for a car?
Take the total mass with passengers and cargo, multiply by gravity at 9.80665 m/s² to get the load carried by the tires, then multiply by the rolling resistance coefficient for that tire and road surface. A 1,500 kg car on asphalt at Crr = 0.013 gives about 191 N of tire rolling resistance, which costs roughly 5.3 kW of power at 100 km/h — before drivetrain losses and air resistance are added on top. The same three numbers work for a bicycle or a fully loaded truck; only the mass and the coefficient change.
What is a typical rolling resistance coefficient?
Ordinary car tires on concrete or fresh pavement are usually quoted at 0.010 to 0.015. Truck tires on asphalt run about 0.006 to 0.01, bicycle tires on asphalt near 0.004, and railroad steel wheels on steel rails around 0.001 to 0.002. Loose sand is in a different league entirely, at 0.2 to 0.4, because ground that deforms under the wheel swallows energy that firm pavement never takes. Treat every published coefficient as a band rather than a fixed number — inflation pressure, temperature, and the test method all move it.
Does rolling resistance depend on speed?
The coefficient is treated as constant for quick calculations, and that is a fair approximation at normal road speeds. In reality it creeps upward with speed and downward with higher tire pressure, which is exactly what the pressure method in this calculator models. Note that the power lost to rolling resistance always rises with speed even when the resistance force does not, because power is force multiplied by speed. That is why rolling resistance shapes fuel consumption most in slow city driving, while aerodynamic drag takes over on the motorway.
Do wider tires have more rolling resistance?
Not necessarily. At the same inflation pressure and load, the contact patch covers roughly the same area whatever the width; a wider tire simply makes it shorter and stubbier, which usually means slightly less casing deformation on every revolution. Wheel diameter, casing construction, and tread compound matter far more than width — and the extra footprint often buys traction and comfort at no real cost in resistance force.
Do low rolling resistance tires save fuel?
They save some, but the effect is smaller than the marketing suggests. Published estimates put a 5–7% reduction in rolling resistance at roughly 1% better fuel efficiency, and the compounds that achieve it can trade away a little wet traction and tread life. Correct tire pressure, a lighter load in the boot, good alignment, and healthy wheel bearings cut the same resistance force for far less money — so unless you are racing, spend there first.
How much does bicycle rolling resistance cost a rider?
For an 85 kg rider-and-bicycle combination on smooth pavement the force is roughly 3.3 N, which works out at about 19 W of power at 20 km/h and 28 W at 30 km/h. That is a meaningful slice of a recreational rider's output at city speeds, so supple tires, a good tube, and sensible pressure are cheap free speed. Push past 30 km/h and aerodynamics dominates, but the rolling loss never goes away — it just stops being the thing worth fixing first.
Is rolling resistance the same as friction?
They share a formula but not a mechanism. Sliding friction comes from two surfaces rubbing past each other; rolling resistance comes mainly from energy lost inside material that deforms and springs back imperfectly. That is why a rolling coefficient is typically ten to a hundred times smaller than a sliding friction coefficient for the same pair of materials, and why the wheel is such an efficient invention. Bearing friction and drivetrain drag are separate losses again, though a coast-down test on the road lumps all three together.
Does extra weight increase rolling resistance?
Yes, and in direct proportion. Doubling the load on the wheels doubles the normal force and therefore doubles the resistance force, which is why a laden truck fights the road far harder than an empty one. Mass is the one term in the formula you can change without touching the tires: 100 kg of clutter removed from a car cuts its rolling resistance by the same percentage as a noticeably better set of tires would.
Why might another rolling resistance calculator give a different answer?
Almost always because it picked a different coefficient from the same published range for that tire and surface, or used 9.81 rather than 9.80665 m/s² for gravity. Some tools also fold bearing and drivetrain drag into the figure, which inflates it. This page prints the exact coefficient, mass, and gravity behind every result, so any gap can be traced straight back to its source.
Data sources and assumptions
Coefficients follow commonly published engineering tables for wheel and surface pairings. Standard gravity is 9.80665 m/s². The tire-pressure option uses a well-known empirical estimate for air-filled car tires on dry roads, where the coefficient falls with pressure and rises with speed.
- Engineering ToolBox: Rolling Resistance — coefficient tables in dimensionless and length form, plus the pressure-and-speed estimate.
- U.S. DOE / EPA: Where the Energy Goes — how rolling resistance compares with engine, driveline, and aerodynamic losses.
- Transportation Research Board Special Report 286 — measured rolling resistance across roughly 200 passenger tires and its effect on fuel economy.
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