They come out under the cover of darkness and, while no one is watching, they leave a big and potentially hazardous mess behind.
They're tire dumpers, and in Cleveland, you'll see their waste everywhere -- and these violators know they're almost certain to get away with their dirty work.
"Look at these tires, they're not from a car," says Cleveland Councilman Eugene Miller. "They're from a truck."
In only the past six months, Miller and his staff and volunteers have picked up nearly 2,000 tires in his South Collinwood ward.
But old worn-out tires are everywhere, littering neighborhoods throughout the city.
Bob Stevens, who lives in an East Side neighborhood, can attest to that.
"This is happening on a continual basis, and it definitely has to stop," he says.
On the West Side, Dave Reuse has worked with community service crews to clear more than 1,900 tires in six months. His surveillance team is on the lookout for a 17- to 20-foot white box truck.
"They back into a vacant house's driveway, and it takes less than a minute to kick out about 200 tires," he says. "It upsets me quite a lot."
Old tires can be put to good use -- creating swings at playgrounds, or getting ground up for mulch -- and there's certainly no shortage of them.
Ohio has been called the scrap tire capital of America. If that's the case, Cleveland might well be the tire dumping capital of Ohio.
Here's where things go wrong: when someone buys new tires, they are supposed to pay three or four dollars per tire to dispose of the old ones. But maybe they don't want to.
So they put them in their trunk and just throw them out of their car in a nearby neighborhood.
As Councilman Miller points out, it's usually in a Cleveland neighborhood, not one in Shaker Heights, Bratenahl or Solon.
Stevens lives close to a corner where there are six tire stores. Ethical stores owners pay registered haulers to take tires away; shady store owners use unregistered haulers who offer to get rid of the tires cheaply, for cash. No questions asked.
"It's too easy to do," says Stevens. "Next thing you know, a truckload of tires is dumped at once."
"It's not just five, there's one place where we pick up 50, 60 tires," says Councilman Miller.
There seems to be no downside for the dumpers. They almost never get caught.
The city has arrested one person in the past three and a half years for tire dumping.
"There's signs up that say 'no dumping,' but no one is paying attention because there's no recourse," Stevens says.
During the hot summer months, tire dumping becomes an even bigger concern as water-logged tires create a breeding ground for mosquitoes and disease, including encephalitis.
So why isn't the city more aggressive about enforcement? Mayor Frank Jackson apparently doesn't want to talk about it.
He and his staff ignored several requests over a week and a half for even a five-minute interview to answer questions about tire dumping.