Among the many technology topics on the agenda during the 53rd annual Electric Utility Fleet Managers Conference (EUFMC), a pair of presentations on tire issues was of great interest to fleets operating light- and medium-duty vehicles.
“To optimize tire design and performance, tools like finite element analysis (FEA) allow designers to look inside a new tire while it is still in the idea stage and develop performance requirements, said Matt D’Arienzo, national strategic account manager at Goodyear Tire & Rubber Co.
Treadwear modeling, for example, can show a predicted effect of tire construction changes on footprint shape and contact pressures, D’Arienzo said. An FEA footprint model can be used to tune mold shape and tire construction to provide the best footprint for maximum tread life. FEA is used to predict strains for evaluation of tire bead area durability under overloaded conditions, he said. In addition, computer-based visualization tools have been developed for analysis of laser mapping of the worn tread surface.
“One of the challenges faced during the design process is developing a tire that delivers a good balance of performance properties,” D’Arienzo said. “In the ideal case, the resulting product provides equal improvement for the other performance properties. In most situations, this doesn’t happen. We often have to deal with performance trade-offs when we try to optimize one property. Tire modeling tools provide a way to predict the impact of a design change on tire performance.”
Also affecting tire design and performance are regulations and standards, said Roger Handren, government sales manager at Michelin North America. Current regulatory activity includes tire performance upgrades for cars and light trucks and a change in normal load definitions, from 88% of a tire’s maximum load to 94% of the load rating associated with recommended inflation pressure.
Environmental regulatory activity is increasing, as well. A National Academy of Sciences (NAS) study issued in March 2006 concluded that reducing the average rolling resistance of tires by 10% is technically and economically feasible, Handren said. The report also concluded that rolling resistance has a meaningful effect on fuel economy. But, while traction may be affected by modifying a tire’s tread to reduce rolling resistance, the safety consequences are probably undetectable. NAS went on to recommend that Congress authorize resources to gather and report information on the influence of passenger tires on vehicle fuel consumption.
Technical standards activity by industry organizations includes developing new test standards for accelerated aging, bead unseating, road-hazard impact, measurement of tire belt temperatures, non-destructive tire evaluations, truck road wheel and light vehicle tire highway-equivalent road wheel test speed, Handren said.
“There is some value in all of this activity,” he said. “Standards ensure consistency and interchangeability. It would not serve any purpose to have tires from different manufacturers that were of different sizes or load carrying capacity, wheels that would not fit on another brand of vehicle or tires that require specific wheels by size and brand.
“Regulations can also help by controlling costs, or at least making them more predictable,” Handren said. “They can ensure that tires meet performance minimums, provide more information for the purchaser and level the field so all players have to adhere to the same rules.”