Effects of resistive loads and tire inflation pressure on tire power losses and CO2 emissions in real-world conditions

Considerable portion of energy losses in a vehicle traced to tire. Energy losses in a tire are due to tire longitudinal slip as well as rolling resistance. Hence, both of aforementioned factors must take into the consideration to study the tire energy loss. Present paper aims to investigate the power losses in tires and to examine influence of road conditions and tire inflation pressure on them. To cover the real-world conditions, experiments were done on a gasoline-fueled passenger vehicle on an urban highway along two routes with same length and opposite gradients to comprise the change of road conditions. Then, by use of engine performance model which is prepared in dynamometer laboratory, the power losses in drive and driven wheels are conducted separately. According to the results, either in driven wheels or when cruising in negative gradient, the power loss due to rolling resistance is primary and as a result the tire power losses would be decreased as inflation pressure increases. But when the tractive force is significant, for instance in positive gradient, the role of slip power loss becomes substantial in drive wheels so that the sum of rolling resistance and tire slip losses must be evaluated. Results show that in positive gradient, the least tire power losses in drive wheels would be obtained when the tire is under inflated. In addition, CO2 emissions during the tests obtained and it is seen that a reduction in tire power losses leads to decrease of CO2 emissions.