Calculate rolling resistance

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Rolling resistance is a parameter that counteracts the rotational movementof the wheels on vehicles including cars, pallet trucks or stacker trucks. Unlike starting resistance, which only refers to the force required to start a vehicle, rolling resistance refers to the permanent force that is generated when a wheel rolls and is directed in the opposite direction of the movement. It is also often referred to as rolling friction.

When using transport equipment like transport trolleys, transport trucks or industrial trucks, the rolling resistance of the tires should be as low as possible, as a high resistance leads to higher fuel consumption and greater effort when moving the equipment. With the help of rolling resistance coefficient values and formulas, this guide aims to show you how to calculate and optimisethese resistance forces to save fuel and lower emission values for motorised vehicles.

Rolling resistance formulas: How to calculate rolling resistance of tyres

You can easily calculate the rolling resistance of tyres by using the following steps.

Calculating rolling resistance on a level surface
Rolling resistance (F_R, also called rolling friction coefficient) can be calculated using the following formula:

F_R = C_R x F_N

The resistance results from the rolling resistance coefficient (C_R) and the normal force (F_N). The normal force in this formula refers to the weight force of the transport vehicle in kilograms (kg) on a horizontal road without an incline or decline and without aerodynamic effects such as lifting or pressure on the tyres.
Calculating the rolling resistance coefficient
The rolling resistance coefficient depends on the material properties of the tyre and the road surface, as well as the dimensions of the tyre (R=radius) and the distance travelled in metres (d). The value is necessary for calculating the rolling resistance and can be determined with this formula:

C_R=d/R

The distance (d) is the distance between the point of action of the normal force (F_N) to the centre of the wheel. This offset arises due to the deformation of the tire as it rolls. As the distance (d) depends on complex, non-linear deformation behaviours and material properties, it cannot be determined analytically and serves more as a basic description of the physical effect. This means the rolling resistance coefficient is generally measured experimentally, for example, using test benches.
Calculation of the rolling resistance with known rolling resistance coefficient
The rolling friction coefficient depends significantly on the combination of surface and tyre material and does not have to be calculated on top if there are tables for friction values of different material pairings available. You can simply look up the value and insert it into the calculation formula.
Calculating rolling resistance for forklift tyres
If you want to calculate the rolling resistance for forklifts you must consider not only the weight force of the vehicle and the mass of the load (F_Zul) but also the gravitational acceleration g (g = 9,81 m/s²). When calculating rolling resistance for a level surface, use this formula:

F_R = (F_N + F_Zul) ∙ g ∙ C_R

What influences the rolling resistance of tyres?

Rolling resistance, also known as rolling friction, is not a constant. It depends on various factors:

Tyre pressure

Tyre pressure significantly affects rolling resistance: the lower the tyre pressure, the higher the resistance. Therefore, you should check the tyre pressure of all your vehicles once a month, including your stacker trucks, to ensure it is at an optimal level. If you’re unsure of the correct tyre pressure to aim for or the checking process, follow the manufacturer’s instructions. To prevent accidents and collisions, it is advisable to regularly check the tread of your industrial trucks.

Tyre material

When it comes to achieving the lowest possible rolling resistance, there’s a key principle: the harder the tyre’s surface material, the more easily it rolls. However, it’s important to note that extremely low rolling resistance can negatively impact driving and braking performance. That’s why it’s crucial to match the tyre material to the surface type to ensure that forklifts, transport equipment, and similar vehicles are operated safely:

For slippery surfaces like tiles or linoleum, softer air-filled tyres are the best choice. These provide a better grip on smooth surfaces while maintaining good rolling resistance.
When dealing with hard surfaces such as asphalt or rubber flooring, it’s best to use polyurethane or rubber tyres. The nearly maintenance-free PU tyres offer relatively low rolling resistance and good shock absorption, even on uneven and challenging terrain.
To achieve the lowest possible rolling resistance on hard floors, polyamide (nylon) or steel tyres are your best bet. These materials are ideal for hard surfaces in hygiene-sensitive or other demanding environments due to their resistance to grease, alkalis, and acids.

Tyre design and dimensions

Modern fuel-saving or low rolling resistant tyres are characterised by a resistance-optimised construction that reduces the deformation of the tyre while driving. This deformation, along with the choice of material, is largely responsible for the rolling resistance.

Generally, wide and flat wheels have a higher rolling resistance than taller, narrow ones. However, this principle also depends on the surface. For example, vehicles with narrow tyres require a more significant effort to move on soft surfaces like sand. In such cases, wider tyres are better suited to minimising rolling resistance.

Tyre age

It is more difficult to move cars, trucks or forklifts with older and worn tyres than with new ones. However, even new tyres may temporarily have more resistance until they are broken in.

FAQs about the rolling resistance of tyres

What is the rolling resistance of tyres?

Rolling resistance is a force that works against the rotational movement of wheels on vehicles like cars, pallet trucks or forklifts. When driving or using transport equipment, trucks, and industrial vehicles, it’s important to keep the rolling resistance as low as possible. High resistance leads to increased fuel consumption and/or requires more effort when moving manual transport equipment.

What’s the difference between rolling resistance and starting resistance?

Unlike starting resistance, which only refers to the force needed when starting to move forward, rolling resistance is the constant force that is generated as a wheel rolls opposite to its motion.

Why should the rolling resistance of tyres be as low as possible?

The higher the rolling resistance of tyres, the more energy is needed to move the vehicle forward. For transport vehicles covering about 50,000 kilometres (about 31,000 miles) annually, using tyres optimised for low rolling resistance can save several hundred pounds a year. Even for manual transport equipment, it’s advisable to aim for low rolling resistance as this makes transportation quicker, easier, and more ergonomic – which is better for both people and machines.