For several years, a joint work between Michelin and INRAE has been launched to define a protocol for evaluating traction efficiency using a specific test bench allowing the tire to be tested in real usage conditions while controlling and measuring all the influential external parameters.

Considering the variety of uses and types of soil encountered by an agricultural tractor, it is important to be able to differentiate the different sources of energy loss in the interaction of the tire with the ground to assess the influence on vehicle consumption. To achieve this, a hybrid method with experimental measurements and modeling has been developed to evaluate tire rolling resistance, ground compaction and slipping losses, relatively to use conditions (soil, nature of the work, load, pressure….).

In this work, the first results on soft soil, using ENTAM protocol, show a great importance of energy loss due to soil compaction and tire rolling resistance specially at low tractive effort. At higher traction, slipping losses became preponderant. Thus, the tire design and pressure management could be adapted to the usage to improve energy efficiency. This approach allows to feed a life cycle analysis tool for different types of usage and vehicles; this work shows that a major part of the environmental impact of the tire is due to the use phase of the tire on vehicle.