BMW UK says the new electric i3 electric "defines the car of tomorrow", a sizable claim backed up by exclusive tire supplier Bridgestone, who describes the i3 as representing a "milestone in automotive history". With a lithium-ion battery that offers a range of 80 to 100 miles, the i3 is by BMW UK’s admission ideally suited to urban driving; indeed, the car maker claims that "every detail and every feature" pertaining to the new electric car is designed for life in the city.
The tires designed specifically for fitment on the i3 required, says Bridgestone, the adoption of an entirely new concept. The answer was something it calls ‘ologic technology’. As seen in the “Large & Narrow” concept tire shown at last year’s Geneva motor show, ologic technology capitalizes on the synergies of a large diameter coupled with a narrow width and tread design. Bridgestone says such tire dimensions significantly improve aerodynamics and rolling resistance while offering outstanding wet grip, a claim it bases on the results of comparative tests (using a size 155/55 R19 tire against 205/50 R18 and 175/65 R15 fitments) carried out at its Tochigi proving ground in Japan in 2011.
How can a tall, narrow tire be both aerodynamic and good in the wet? Bridgestone explains that while the tread on smaller diameter tires is typically inclined to excessive movement or “deformation” during driving, a larger diameter and higher belt tension significantly reduces tire deformation and therefore conserves energy that is otherwise lost through internal friction and this helps to reduce rolling resistance. By the same token, the narrow tread concept improves aerodynamics. Yet in Bridgestone’s opinion the most spectacular achievement ologic technology provides is that these improvements do not involve a trade-off in terms of safety. The tire’s long contact patch (relative to its narrow width), along with the choice of tread design and compound, aid grip in both wet and dry conditions.
“The BMW i3 is very much a car for the future,” commented Franco Annunziato, CEO and president of Bridgestone Europe. “Developing a unique tire for this unique vehicle was therefore an enormously challenging but also rewarding experience. Energy efficiency is an important development criterion for all our tires at Bridgestone. However, it becomes an even more critical factor in an electric car. Which is why we have put all our knowhow, skill and passion into developing this unique tire concept. One that we are confident delivers the premium performance, safety and economy towards consumers who have come to expect it from both brands.”
Released together with the BMW i3 in November 2013, the Ecopia EP500 ologic tire is available in four sizes 155/70 R19 84Q, 175/60 R19 86Q, 155/60 R20 80Q and 175/55 R20 85Q and two winter varieties the Blizzak LM-500 ologic and the studless Nordic-conditions Blizzak NV ologic. This second tire features Bridgestone’s Multicell compound, which contains microscopic bubbles and tubes that clear water rapidly from between the tire and ice or snow surface to improve contact of the tire on the road. As the water is cleared, the ‘bite’ particles come into contact with the ice surface, improving the grip even further. (Tyres & Accessories)