I would like to respond to the two letters referring to the author's belief in studded tires. The letter written by Dave McRae (Jan 1), has his personal belief in studs based on his experience with black ice and a slide through an intersection. In both instances his was the fault because he was not driving according to possible conditions at the time. The meteorological statements of his can be discounted, as he provided no objective references, which can be checked. The second letter by Paul Biskup (Jan 8), was so disjointed and rambling that one has a difficult time trying to figure out what the majority of the letter was about. One thing was clear however. He also likes studded tires.
Since neither author seems to be in possession of the facts about winter tires, let me enlighten them and others about this. According to a study done by the University of Alaska Engineering Department comparing studded tires with a modern snow tire, the studded tire has only a slight traction advantage in stopping when new, on polished ice at 32 degrees F. In all other parameters such as snow, packed or new, ice colder that 32 degrees F, and automobile maneuvers, the studded tire was not as effective as a standard approved snow tire. Further, after 1,000 miles of wear was placed on the two types of tire, the studded tire was poorer in every category. The test was run with front wheel drive, rear wheel drive and pickup. Last year Tire Rack, which is a respected tire seller and tester, ran a test on polished ice using three traction snow tires they sell against a studded tire they sell, and found the studded tire was dead last in their tests. Norway found that studded tires give drivers a false sense of confidence and those using them tend to drive more rapidly and therefore increase the risk of an accident.
Now look at the logic of using studs in various snow/ice conditions. Their values in newly fallen snow is zero, in slush zero, in packed snow the modern siped snow tire has many more gripping edges than a few short studs, and on rough ice that one will find on a road surface the siped tire is more grippy again. This brings us to black ice. By definition black ice is not thick. Say a millimeter at most. Since a stud is only 0.06 inch long or approximately 1.5 mm it stands to reason that when on black ice a stud is riding on the pavement beneath, and one is getting only the benefit of a stud on dry pavement. In contrast, the studless snow tire once again has hundreds of gripping edges to hold against. In fact most every tire manufacturer has realized that the modern snow tire is better and most put studs into a tire that is siped.
For most winter days in which there is any road condition that might bring on ice, the de-icer trucks and the sanding trucks are out in full force thus negating the need for any perceived need for studded tires.
Belief based on personal experience is fine when applied to religion, but to deny objective evidence is not logical. Studded tire value is one of those myths, which does not stand up to objective testing.
My personal bias against studs is threefold. First is the destruction they cause to the road. One can see in the bottom of the ruts, the longitudinal cracks which develop. Those cracks let water into the road surface, which causes the pavement to fracture. The next complaint is that the ruts make it dangerous because the car is deflected or trapped when encountering a rut. The third thing is the hydroplaning one encounters when the rut fills with water.
For a few days in the year in which snow tires are needed in Central Oregon, we are creating road safety issues by the use of studs. The safety issues are there whenever the pavement is dry, which is the majority of the year.
The University of Alaska report can be found at http://www.wsdot.wa.gov/winter/studtire.htm It is 60 pages long and has many bar graphs and tables giving the information discovered. Tire Rack is www.tirerack.com
B. Graham, Sisters