I forget the statistic, but there are lots of vehicles on the roads with bald tires. I think it is huge.
Check out what Consumer Reports said
"A recent study by the National Highway Traffic Safety Administration found that nearly 50 percent of the 11,500 cars, pickup trucks, vans, and sport-utility vehicles the agency checked had at least one tire with half-worn tread. Another 10 percent had at least one bald tire."
kinda scary... and it reminds me I need tires.
BTW, I bet this is more common with the economic situation at hand.