What is the rolling resistance of the tyre?
Ever wonder, what is “tyre rolling resistance”? And how it may affect your tyre-purchasing choice and fuel efficiency? Today, we will elaborate on tyre rolling resistance and the means by which low resistance tyres can expand the eco-friendliness of your vehicle.
In order for your vehicle to move, energy needs to be transferred to the engine and other systems in the vehicle. This energy is generated via gas or electricity. That outcomes is your tyres turning and enough force being developed to move your car.
However, your vehicle must conquer a variety of resisting forces that can make it impervious for your vehicle to move forward. One of those resistive forces is the rolling resistance of the tyre.
The key principle of rolling resistance is known as hysteresis. Hysteresis is basically the loss of energy as tyre rolls and overcome resistance. The loss of energy due to resistance must be overwhelmed by the vehicle’s engine.
Excessive rolling resistance is one of the common factors that hurt the life of a car tyre as well as the fuel economy. That is why today tire manufacturers such as Michelin Tires, Goodyear, or Pirelli claim that their tires offer the least rolling resistance to attract more customers.
Calculating the rolling resistance of a tyre
Rolling resistance coefficient (RRC or Crr) is used in expressing the rolling resistance of the tyre. The energy consumption of the vehicle will be less if the rolling resistance coefficient is lower.
Following is the formula for calculating the rolling resistance of tyre:
( N/Lbs) = P^α x Z^β x (a + bxV + cxVxV)
- P is the tyre inflation pressure ( kPa / psi)
- Z is the applied load for vehicle weight ( N /Lbs)
- V is the vehicle speed ( km/h / mph)
- alpha, beta, a, b, c are the coefficients for the model.
Key components affecting tyre rolling resistance
The most significant component affecting the tyre rolling resistance includes:
Weight
The lower weight of the vehicle with tyres, the lower resistance. As a rule, low-profile, limited tyres are lighter, as well as the tyres with lower height have lower rolling resistance.
Aerodynamics
The resistance due to aerodynamics is the opposition of the encompassing air and the drag force. Resistance due to aerodynamics is directly proportional to the speed of the vehicle.
Tyre pressure
Tyres with low air pressure can cause expanded contact of the tyre with the ground while increasing the resistance up to 30%.
Tread design
The elastic compound and enhanced tread design can immensely influence the rolling resistance up to 60%.
Tyres with low rolling resistance
Following are the tyres rated with the lowest resistance coefficient
| Tyres | Rolling resistance coefficient |
| Bridgestone B381 P185/70R14 | 0.00615 |
| Michelin SYMMETRY P225/60R16 | 0.00650 |
| Michelin TIGER PAW AWP P225/60R16 | 0.00683 |
| Bridgestone DUELER H/T 113S P265/70R17 | 0.00700 |
| BFGoodrich RUGGED TRAIL T/A P285/70R17 | 0.00709 |
| Michelin LTX A/S P255/65R17 | 0.00754 |
| Goodyear INTEGRITY (OE) P225/60R16 | 0.00758 |
| Bridgestone INSIGNIA SE 200 89S P195/65R15 | 0.00760 |
| BFGoodrich RUGGED TRAIL T/A P245/65R17 | 0.00767 |
| Continental Ameri-G4S WS P235/75R15 | 0.00780 |
| Continental CrossContact LX | 0.00783 |
| Michelin TPAW TOURING TR/SR P215/70R16 | 0.00795 |
| Bridgestone DUELER H/T 104S P235/70R16 | 0.00810 |
| Goodyear Invicta GL 235/75R15 | 0.00813 |
| Continental ContiTouring Contact CH95 P205/55R16 | 0.00825 |
| Michelin CROSS TERRAIN SUV P255/75R17 | 0.00829 |
| Michelin PILOT PRIMACY 275/50R19 | 0.00833 |
| Michelin ENERGY LX4 P225/60R16 | 0.00850 |
| Michelin PILOT LTX P265/70R17 | 0.00854 |
| Michelin ENERGY MXV4 PLUS 235/65R17 | 0.00855 |
Apart from fuel efficient and eco-friendly tyres such as Michelin pilot sport 3 are manufactured for the sole purpose of providing high performance.
Rolling resistance coefficient values for energy efficiency
| Cl tyres | C2 tyres | C3 tyres | ||||||||
| RRC in kg/t | Energy efficiency class |
RRC in kg/t | Energy efficiency class |
RRC in kg/t | Energy efficiency class |
|||||
| RRC 6,5 | A | RRC | 5,5 | A | RRC | 4,0 | A | |||
| 6,6 12ItC | 7,7 | B | 5,6 | fklIC | 6,7 | B | 4,1 | 12ItC | 5,0 | B |
| 7,8 .1kFtC | 9,0 | C | 6,8 | IztRC | 8,0 | C | 5,1 | 1,tFtC | 6,0 | C |
| Empty | D | Empty | D | 6,1 | 17tRC | 7,0 | D | |||
| 9,1 1,tFtC | 10,5 | E | 8,1 | 1:tRC | 9,2 | E | 7,1 | 1,(F&C | 8,0 | E |
| 10,6121kC | 12,0 | F | 9,3 | FtIkC | 10,5 | F | RRC | 8,1 | F | |
| RRC 12,1 | G | RRC | 10,6 | G | Empty | G | ||||
Final words
Tyre rolling resistance is the 70% of resistive forces acting upon a vehicle, that is the reason it is very important to keep the rolling resistance coefficient of the tyre low.
Resistance is one of the vehicle energy shoppers. Decreasing the rolling resistance of tyres prompts a decrease in fuel utilization and carbon dioxide emissions.
A tyre maker can lessen tread depth in order to counter rolling resistance. Nevertheless, there will be a comparing decrease in tyre wear life. To beat this, innovations are being worked on in order to beat rolling resistance while keeping the tyre wear life prolonged.