Functions of tire, i.e. to support the vehicle load, to roll, to lessen shocks, and to curve and stop safely, are not different with EVs compared to vehicles powered by internal combustion engine. If a difference is sought, since effective use of energy is an urgent issue of the current EVs, the reduction of rolling resistance is believed to have a high priority. Although reduction of rolling resistance is a major technical theme in the current tire development, there is no specific area unique to EVs. On the other hand, if ordinary tires are installed on EVs, a difference in rolling resistance that is not usually recognized might become apparent. Accordingly, some tires are claimed to be exclusively made for EVs so that users can easily choose low rolling resistance tire.

  Fuel economy of an actual vehicle largely depends on vehicle model, tire type and driving conditions. The influence of the tire on the fuel economy of passenger cars is believed to be 5 to 15% under normal running conditions.

Factors related to the generation of rolling resistance can be divided as follows:

1. Energy loss caused by hysteresis loss occurred on the tire due to deformation of the tire while rolling
2. Friction resistance generated between the tire and the ground surface

(1).Friction generated in area of the grounding surface of tire
(2).Sliding friction generated during acceleration and deceleration
(3).Drag component of cornering power generated while performing toe-in and cornering
3. Air resistance

Reference
Book title: EV Handbook
Written by: EV Handbook Publisher's Group
Published by: Maruzen Co., Ltd. (URL http://www.maruzen.co.jp)