Bob Wade's boots could stomp a bus. Wade's boots are so pretty they could strike Ralph Lauren blind; their vamps are ersatz ostrich skin, their uppers phony calf. They're as out of place in Washington as that scar on LBJ.

Bob Wade is a Texan Texans can relate to. When shoppers stop to ask him what the hell he's building on that downtown vacant lot at 12th and G Streets NW, Wade gives it to them straight.

"The Biggest Cowboy Boots in the World," he says.

They are not quite ready. They are custom jobs, of course, and custom jobs taken time.

Wade's 42-foot boots still lack their stirrup-gripping heels, their pimpled pulls and piping, but he says that they'll be done tomorrow, and he's an artist of his word. He's going to leave them there for three months.

Wade, 36, says his art is "about Texas." He graduated from the University of Texas at Austin in 1965 with a degree in painting, and had his first show in Waco two years later. For the Bicentennial year he constructed a map of the United States in Dallas that stretched 100 yards from sea to shining sea.

I chose football-field size, something Tecans could relate to," says the artist, whose work for years has drawn on the tall tales and myths of the Lone Star state.

Wade's art is good-natured. He could have darkened that corner with black motorycycle boots four stories high, or shiny British jodhpurs with skinny straps buckled on the side.

His boots are friendly, neither frightening nor prissy. They do not, despite their size, intimidate the loafers, wingtips or gymshoes of the tiny passersby.

The effect is Texan to a T. First of all, it's big, and bigness, estheticians know, is one path to the beautiful. Pyramids the size of paperweights would not be impressive, nor would the Washington Monument were it 5.5 feet high. Wade's art is not difficult. What you see is what you get.

Once Wade's map was fininshed (its Great Lakes, Rockies, roadsigns and highways were built approximately to scale), he constructed "The Texas Mobile Home Museum" and exhibited it in France. His shining rebuilt metal trailer was "customized" with ropes, leather belts, and chrome-plated barbed wire. Inside, viewers gaped at two-headed calves, huge snakes, "The World's Longest Pair of Longhorns," and other believe-it-or nots. Then in 1973 Wade went North to Artpark near Niagara Falls and there built a 40-foot iguana.

When purists complained that Texas cannot boast indigenous iguanas, Wade explained that he was "sick of armadillos."

"You've heard the expression," he adds, "a Texan is a Mexican on his way to Oklahoma."

Wade's lizard now glares down on Manhattan's Fifth Avenue from the roof of the Lone Star Cafe, a saloon the artist describes "as a real jumping place."

It was Al Nodal, director of the Washington Project for the Arts, who suggested that Wade build on the vacant lot downtown. Similar invitations have been tendered to Rockne Krebs, Alice Aycock, Yuri Schwebler, Nade Haley, Martin Puryear, and to other artists. Though Washington, of course, is full of sculptured boots (most are worn by heroes riding on bronze steeds), those built by Bob Wade are gaudier than most. And they cost $7,000.

They are made of wire stretched across an armature of metal pipes. Plastic foam was sprayed upon the wire. Close up, the pimples on the ostrich skin look like fungoid blobs. "That's where the feathers went," says Wade.

Various companies and institutions, both public and private, have helped pay for Wade's boots. The Hotel Washington housed the artist for six weeks. The city's government lent the land. Downtown businesses of many sorts came up with small grants. An additional $3,000 for the WPA's continuing "Washington Art Site Project" was provided by the federal government's National Endowment for the Arts.