Previously, tire testing rules for the winter tires were the same as other passenger vehicle tires, which opponents claimed subjected the tires to more severe standards than they would face in real-world use.
The NHTSA modification also excluded specialty radial light truck tires with tread depths of 18/32nds or deeper from VFMSS 139 standards. Instead, those tires will continue to be tested under FMVSS 119 standards.
The revision reduced endurance and low-pressure test speeds for winter-specific tires from 120 kilometers per hour to 110 kmph.
NHTSA issued the new TREAD Act-mandated safety testing standards in June 2003, but various specialty tire makers and industry association filed petitions for reconsideration, claiming the increased standards would seriously hurt specialty tire producers.
The revised regulations take effect in September 2007.