# Is a wider tire bad for the transmission?

## Rolling resistance in tires

Rolling resistance: We explain how it is created, what influence it has on fuel consumption and whether there are also tires without rolling resistance.

• Rolling resistance is a necessary evil with rubber tires

• Correct tire pressure reduces resistance and saves fuel

• Already knew? With a metal tire, the rolling resistance is zero

### How does rolling resistance arise in car tires?

If you want to move forward, you have to overcome resistance. This also applies to car tires. When aTire starts moving, the tire casing deforms and relaxes. The tread and the tire flank are bent, compressed and sheared. Depending on the compound and profile design of the tire, this consumes more or less energy, primarily asHeat loss is lost in the tire.

TheThe force required for the rolling movement is called rolling resistance. It is directly dependent on the wheel load. The higher the wheel load, the higher the rolling resistance. The measure of rolling resistance is the rolling resistance coefficient, which relates the rolling force to the wheel load and is usually given in percent

### What other driving resistances are there?

When driving on a level road without inclines or declines, the total road resistance of the vehicle is made up of thefour following individual resistors together, which have different effects on the car depending on the driving situation:

• aerodynamic forces (Air resistance)

• Frictional forces of the vehicle (e.g. frictional resistance in the engine or gearbox)

• Inertial forces (Inertia of the vehicle mass)

• Rolling resistance the mature

For example, when driving fast on the motorway, the share of aerodynamic forces in the driving resistance is very high, while in city traffic with constant braking and starting, energy has to be expended against the inertial forces. TheShare of rolling resistance in total driving resistance is between 30 percent in the city and around 20 percent on the highway.

### How does rolling resistance affect fuel consumption?

Theoretically yes. For a metal tire that does not deform, that would beZero rolling resistance. But would such a bike brake well, drive around corners with grip or offer suspension comfort? No, only a rubber tire with a wide contact area, profile against aquaplaning and springy air filling can do that. The properties of the tire rubber are important for driving safety, but they cost fuel.

TheSo tire rolling resistance is a necessary evil, but the tire industry is working to optimize it. Bynew rubber compounds or constructive changes to the tire substructure, the energy absorption and the associated rise in temperature should be reduced. Tires with the additional designation "Energy" or "Eco" are already available - what they actually do in terms of rolling resistance is in theADAC tire tests.

### Are there also tires without rolling resistance?

Theoretically yes. For a metal tire that does not deform, that would beZero rolling resistance. But would such a bike brake well, drive around corners with grip or offer suspension comfort? No, only a rubber tire with a wide contact area, profile against aquaplaning and springy air filling can do that. The properties of the tire rubber are important for driving safety, but they cost fuel.

TheSo tire rolling resistance is a necessary evil, but the tire industry is working to optimize it. Bynew rubber compounds or constructive changes to the tire substructure, the energy absorption and the associated rise in temperature should be reduced. Tires with the additional designation "Energy" or "Eco" are already available - what they actually do in terms of rolling resistance is in theADAC tire tests.