It is difficult to become emotional about tires except when they – literally – let us down. But tires are set to get smarter, communicate more effectively and react to changing road conditions. Each of these will play a role in meeting the demands of autonomous- and electric-vehicle (AV/EV) development. “They will be tires that take care of themselves and provide highly supported driving,” said Dr. Philipp Struck, Continental Tire’s head of tire line development. “Mobile data will be essential as we become more autonomous and drive more EVs.”
Rims that automatically adjust width to achieve the optimum tire footprint for specific conditions are now the subject of extensive joint research between tire and road wheel manufacturers. Focus is also on AV systems that would recognize tire punctures, source nearby replacement/repair, vector to the required retailer for the necessary work and then recommence the programmed journey without involvement of the occupants.
Less resistance and carefree tires
Continental uses the acronym CASE (Connected Autonomous Shared Electric) to list divergent mobility needs in the tire business. Trends include maintenance-free (“carefree”) tires, increased comfort requirements and the shift from ownership to usership fleets. EV tires will need to deliver advances in load capacity along with decreased rolling resistance to boost range. “EVs may weigh up to half-a-ton more than a regular ICE-propelled vehicle,” Struck explained. “That means the need for higher inflation pressure, causing a potentially higher wear rate.”
An EV’s ability to produce maximum torque from step-off is particularly challenging for stop-and-go delivery use. “Of course a high, narrow wheel cannot be put on an electric vehicle as an afterthought,” Struck (left) said, noting there are currently 139 tire sizes and specifications for EV and hybrid cars. “We are in constant interaction with manufacturers to figure out what is needed. And of course, top of our list of criteria is safety, always safety.”
Continental’s latest EcoContact 6 spans fitments from the Fiat Panda to BMW’s X5, with diameters from 13- to 22-in., and section widths from 145 to 315 mm. Conti claims 15% less lowering rolling resistance, 20% better wear and 6/2% better wet/dry braking performance compared to the previous-gen EcoContact 5. It also claims its latest Green Chili compound (using vegetable-based oils vs. carbon-based) helps reduce CO2 impact.
The next generation of Continental tires (it has 80 in development, using up to 40 rubber-compound variants) will include asymmetric ribs and sipes, with additional silica content and an optimized polymer network to enhance connection between the silica and rubber. Other goals include higher silicon content for reduced tire deformation and more precise groove-to-sipe ratios combined with lower rolling resistance. Confirmed OE EV applications include the Mercedes-Benz EQC, Porsche Taycan and fitments for VW, Fiat, Ford, Mercedes-Benz, Porsche and Kia.
Adapting to road conditions
Two Continental technologies – ContiSense and ContiAdapt – provide continuous monitoring of tire condition and adapt performance characteristics to road conditions. ContiSense involves electrically conductive rubber compounds that permit tread depth and carcass temperature data to be sent from a sensor in the tire. Penetration of the tread by a foreign object will trigger a warning before pressure begins to be lost. Continental plans to further refine the system’s ability to read road-surface conditions, including temperature and snow.
With ContiAdapt, micro compressors are integrated into the wheel to adjust not only the tire pressure within a variable-width rim, but the size of the contact patch. Four combinations are available: wet, uneven, slippery and normal. Low rolling resistance is achieved on smooth roads with the tire at high pressure, added grip on a slippery surface when pressure is lowered to increase the contact patch. For tackling snow or a stretch of black ice, pressure may be lowered to only 1.0 bar (14.5 psi).
Complementing this technology is a Continental concept tire that has three differing tread zones for three distinct surface conditions: slippery, wet and dry. As tire pressure and rim width change, the tread zones and the tire footprint morph. Continental considers its technologies in R&D as “promising solutions” for EV and AV applications. Will there always be some element of compromise in tire design? “Yes,” said Struck, “otherwise we would just have a single specification!”Continue reading »