Dear Tom and Ray:
The other day, I installed winter tires on my car (I have those tires on separate rims, so I can do this myself). Prior to attaching the wheels to the car, I checked the tires for any damages I might have overlooked last spring. Apart from one or two pea-size pebbles, I noticed quite a few very small pieces of gravel that had lodged themselves in the small crevices of the tread. I cautiously removed all those gravel bits — but while doing this, I wondered, Don't those embedded pieces of stone somehow resemble the studs or spikes we used to have on winter tires (which have since been outlawed where I live)? Maybe I should intentionally allow small pieces of debris to collect there. My question is: Am I doing the right thing when I remove those bits of stone, or should I instead take the car for a spin in the gravel pit to create "instant studded tires (just add stones)"? — Wolfgang
Tom: It's "Eureka!" moments like these that lead to great inventions, Wolfgang.
Ray: Notice we said moments like these. Not this one in particular, Wolfgang.
Tom: Unfortunately, the pebble theory has a couple of flaws. If you managed to embed enough pebbles in your tire to make a difference on ice, you'd run into the same problem that studded tires have: That is, they're awful on wet and dry roads — or any non-icy surface.
Ray: Think about it. You're essentially driving on little pieces of metal (or stone, in your case) instead of on rubber. And to make it worse, the pebbles are much more random in size, and therefore are less controllable and predictable than even the lousy studs.
Tom: But you don't have to worry about that, Wolfgang, because the pebbles won't stay in there anyway. As soon as you reach any kind of decent speed, centrifugal force will throw most of those stones out, banging them against the underside of your car and the windshields of the poor schmoes driving behind you.
Ray: So file it under "interesting theories, still in development," and take out the pebbles, Wolfgang.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk website.)