larry (10/28/82)
In a previous article (on snow tires) I made a comment that it would be VERY foolish to mix tire types in the winter. I have gotten a few responces back wonder about this. Here's the cause and effect: [assume all other aspects of the tire are the same] We all know that the difference between a radial tire and the various other types is the orientation of the cord material that holds the rubber together. (hmm, just realized this will be difficult to explain without pictures!) When driving in a straight line, the tread on ANY tire is aligned with the rim of the wheel. However, when you turn the forces make the tread move "out from under" the rim of the wheel. This happens on ALL tires, the problem is that it happens at different points in the curve and at different rates for bias vs radials. (this is sometimes called 'squirm') When you drive a car with all four tires the same design you don't even notice that this happens --its all part of the "feel" of the car. When you switch one end (front or rear) but not both the change can be quite remarkable. Not very noticable in urban driving perhaps, but on a country road at over 50, you will swear that some giant "pushed" your car when you go into a curve. It's a "livable" condition to have bias on the front, radials in the rear in good weather, but in the winter you certainly wouldn't want any "surprises" when you go around a slick bend --the weather provides enough--don't argrevate the situtation with 'funny' tires!! Larry Marek Bell Labs Naperville