SALEM, Ore.—A recent study on the use of studded tires in Oregon found that their use has declined by half since a previous survey conducted by Oregon's Department of Transportation (ODOT), and use of non-studded traction devices are as effective if not more efficient.
The new study of studded tire use in the state indicates drivers have changed their habits, according to the ODOT. It quantifies the current use of studded tires, the pavement damage caused by that use and the cost of repairing the damage.
According to the study's findings:
• The number of vehicles using studded tires has dropped by 75 percent in Oregon—a previous report published in 2000 determined that about 16 percent of registered vehicles in Oregon were equipped with studded tires; the 2014 survey found a reduction in that number to about 4 percent.
• The number of axles on which studded tires are placed per car has grown—the 2000 report determined that studded tire placement was a mix of one or both axles; today almost all cars using studded tires place them on both axles.
• Combining these two results, the latest study concludes that the use of studded tires in Oregon has declined by half since the previous survey.
• The study found wide ranges of wear rates for different kinds of pavements, reflecting the many factors that contribute to pavement rutting.
• Based in part on an overall reduction in the use of studded tires, the increasing popularity of all-wheel- and four-wheel-drive vehicles, and the increased use of non-studded winter tires, the research indicates the use of studded tires will continue to decline, the ODOT concluded. Therefore, “the resulting damage to Oregon's highways, streets and roads and the costs of repairing studded tire damage are expected to continue to decline.”
The study measures the cost of damage from studded tires several different ways and uses multiple estimates of how pavement wears down to determine ranges of damage estimates and repair costs, according to the ODOT.
• One way of determining repair cost is by assessing damage that already has occurred. In 2012, studded tires caused an estimated $8.5 million in damage to Oregon highways. This calculation was developed by looking at effective pavement damage—damage sufficient to require repaving before the pavement surface would normally be repaved, the agency said.
• Another way of determining repair cost is by assessing future expected damage. Using this calculation, the ODOT said the study predicts the cost to repair studded tire damage to Oregon's highway system from 2012 to 2022 to be about $44.2 million, assuming the normally expected pavement design life.
A summary of previous research reviewed in the new report concludes that non-studded traction devices are as effective as or more effective than studded tires in most driving conditions, the agency said, noting that it “encourages drivers to consider using alternatives such as chains or non-studded traction tires.”