So I'm driving in to work, deeply mired my usual commuter's stupor, crawling (and crawling, and crawling) by the junk that lines the side of the 405: glass; underwear; big, tattered sheets of plastic, billowing against the fence on the divider; and the remains of tires.

Huge, hulking truck tires, all torn to pieces and shreds. Long strips of steel fibers and worn black rubber, left to rot by the side of the road.

I used to wonder where these came from. They obviously come off trucks, yeah, but the tire bits are so common that -- heck -- maybe they just fall off, and nobody driving next to the truck would even notice.

I don't hear it, but up ahead there's a truck pulling over to the side of the road. As it starts to get over, an extruded black circle spits out from the back, bounces along heavily for a bit and comes to rest -- smoking; literally, with soft grey-white wisps being pulled out of it by the wind off passing cars -- just outside the slow lane.

The tire -- what remains of the tire -- is huge, and, at 50 miles an hour, would have quite happily squashed my car (and, say, anybody in it) if I'd been in its way. I quietly resolve never to drive behind big trucks ever again. Assuming, of course, I ever drive again.

I used to wonder where those skid marks that zip out of one lane, across two others and into a crumbling part of the freeway divider came from, too, but now I don't wanna know.