Carl Jackson has made a heaven out of many motorists' hell: the seemingly demoniac possession of hubcaps by Washington area highways.

"I advertise '101,000 hubcaps,' " Jackson said, looking at the racks and rows of wheel covers in his Silver Hill store. "But there's, oh, 30,000 here and probably more than that at home."

Some people might call that a monument to folly--a pyramid of potential scrap, the thrown horseshoes of modern Mustangs.

"They don't do anything," Jackson admits, gently flexing his wrist against the weight of an old Corvette rally wheel cover. "They're just pieces of automobile vanity. But we're a car-conscious society. See there?" He points to a barren Chrysler going by. "That's tacky."

Jackson, a 26-year-old lapsed graduate student, and his brothers Tom and Paul, own Hubcap Heaven, an "emporium" of spinners and rims and wires off Branch Avenue.

The Jacksons have been in the business for about three years. Until recently, theirs was a casual outdoor operation, conducted on a Branch Avenue lot. Now they deal their wheels from a pegboard "showroom" two blocks away in a gutted dry cleaner's store near Iverson Mall.

It is half heavy metal, half pop art--floor-to-ceiling steel and foil, sunbursts and solids and grills and wire. The geography is generic: foreign-car covers racked on either wall, 14-inch Chrysler wheelcovers back-to-back with 15-inch, wire wheels over the counter.

"We just thought there was a need there to be filled," said Carl Jackson, who was a Phi Beta Kappa at the University of Maryland who couldn't get into medical school. "We can save people a lot of money."

Earth is indeed crammed with heaven, as far as Jackson is concerned, for metropolitan Washington has become a pothole paradise.

Jackson, in turn, has become a scavenger of the asphalt jungle. He knows the urban hunting grounds--the Whitehurst Freeway, I-295--and regularly cruises the back roads, seeking out the poorer shoulders where the battered covers roll.

"I picked up a Rolls-Royce hubcap on the Southwest Freeway once," Jackson recalled, "and then a couple of weeks later I saw a Rolls the same color on the B-W Parkway. I sort of checked around his wheels Jackson was riding a motorcycle at the time and he was missing one, so I flagged him down and said, 'I think I've got your hubcap.' "

Jackson sold the cover back for $40. "I had done some research," he said, "and a new one would have cost him$ 218: $180 for the hubcap, $18 for the rim and $20 for the paint."

Jackson orders some hubcaps from the factory, and buys others second-hand from flea markets and salvage yards. He has bought out whole collections at a time (including a row house-full in Baltimore), but he still gets a lot of walk-in trade from work crews who sell their roadside acquisitions for cigarette money.

"The problem with the ones found on the road is there's usually some reason they came off," Jackson said, but he pays the crewmen $1 for the average hubcap, "$5 if it's something really special." He resells the average hubcaps for $2 to $6.

Even with 60,000-odd hubcaps, Hubcap Heaven is just a medium-sized concern.

"I know a guy in Easton, Pa., who has a store the size of a Safeway," Jackson said. "He's got license plates that say 'HUBCAP' and . . . I'd guess he's got 150,000 hubcaps."

And even that's nothing compared to the story of a Memphis woman called Hubcap Annie, who was featured on "Real People" claiming to have made several million dollars (and offering to franchise her name for $20,000).

Jackson makes a face. "I don't know about that. There's no millions in it that I can see. But it's better than running a pizza joint."

Like any collector, Jackson still has his special passions, pieces that are not for sale. One is a custom-painted Rolls-Royce hubcap, banded in cream with deep blue pinstripes; it hangs next to a Bentley cover he bought for a dollar at a flea market.

He also has two hubcaps for 15-inch Mercedes limousine wheels, not extraordinarily expensive--about $275 apiece new--but rarely imported. "It's probably a $100,000 car; the wood for the dash is from selected forests, the leather is from cows that graze in unfenced pastures so the hides won't be marked. . . . "

Jackson grins. He drives a 1966 Fury, and it's got every one of its hubcaps.