The roads are alive with the sound of a showboat on wheels.

The sound coming from the theater is so loud that the building vibrates and people waiting in line for the free show can feel it outside. Then the door opens and a group of teen-agers and young adults file out; they're smiling.

"Good graphics. Good audio," says one man.

"Can we see it again?" one teen asks his adult chaperone.

Others are milling around, looking at the exhibit outside, which includes an interactive television display device.

This type of high-tech entertainment is nothing new in Southern California, where amusement parks for years have offered 3-D video with surround sound and audio-animatronics, with virtual reality just around the corner. But this particular $1 million audio-visual exhibit left Long Beach to go on the road this month for 75 appearances across the nation.

The 80,000-pound "Tour de Force" is portable. It sort of folds into itself within a giant trailer so it can be driven across country by veteran trucker Les Hunnel, who gave up hauling freight last winter to become its showmaster. It's owned by Long Beach-based Kenwood USA, which hopes the traveling commercial will help the 30-year-old stereo company become a household word by this time next year.

"It's not like Sony. Everybody knows Sony. Many people don't know us," explains Kristina Mason, public relations manager for Kenwood USA, a subsidiary of Kenwood Japan. "We're just looking for more corporate awareness. We're an entertainment company. We don't just sell stereos."

The Tour de Force made its Southern California debut, appropriately enough, at the Long Beach Grand Prix expo April 10-12. It will visit the majority of the Trans Am races scheduled by Sports Car Club of America in the 1992 season. Spread out against the back wall, it took up about 20 percent of the available floor space in the Long Beach Convention Center arena.

"Our competitors have been coming by, scoping us out, taking notes," Mason says proudly.

As interested race-goers happen by, they initially see a BMW, outfitted with the latest car audio system, and a display of different car stereos and speakers, much like that seen in a car audio store. Except this display includes an interactive television program that allows patrons to enter their cars' model and make and receive recommendations on the type of stereo they should purchase, complete with estimated price. Other interactive screens provide pictures and information on Kenwood's host of other products -- everything from two-way radios to telephones.

All these displays, plus products in glass cases, are under a tent connected to what appears to be an empty truck. Every 15 minutes or so, patrons are invited inside the truck to view a "video" on Kenwood products, which is a short fantasy adventure film in the "Captain EO" genre, minus the 3-D glasses, but complete with special effects, the illusion of motion and sound coming from all directions. It was filmed, in part, at Paramount Studios.

"We don't want to have subliminal advertising, messages saying 'Kenwood, Kenwood,'" says Mason, although Kenwood and its logo are featured throughout the video. "We didn't want just an informational video about products. We wanted to have something that lets you get carried away with your imagination."

The products, the interactive monitors and the video are all most patrons see, and that's more than enough. But there is much more to this attraction on wheels.

If the display, for example, is visiting a Kenwood dealer, and a patron expresses interest in purchasing a state-of-the-art system for his home or car, he may be escorted by the dealer's salesperson into the truck's VIP lounge, which lies between the cab and the theater. Inside is a small living area, complete with coffee maker, fridge, blender (for making margaritas, according to trucker Hunnel), a microwave, a fax and phone, two-way radios, a video monitor, a ham radio, a stereo (of course) and (concealed behind cabinets) the computer system that runs the video.

"At dealer shows, some people come in and see the video, do the touchy-feely thing, and buy something right away," explains Mason.

But at racetrack sideshows, nothing is for sale. The whole exhibit is designed strictly to increase awareness, although Mason says the company will soon be handing out catalogs of Tour de Force clothing. People who express a genuine interest in purchasing equipment are referred to a 1-800 number or to a dealer in their area.

When it's not used to coax VIPs, the lounge doubles as a refuge for Kenwood employees. And there is a balcony area, above the theater, from which patrons can view the race (or in the case of the Long Beach Grand Prix, view the expo). When the Tour de Force is outside, the upstairs patio area can be outfitted with lounge chairs and a bar as a trackside observation deck.

All of this folds up inside the 16-wheel "theater" trailer. The top deck is lowered, becoming a sort of ramp, through which up to two demo cars can be driven inside. Then the floor is raised hydraulically, making room for storage of the audio equipment and displays underneath the cars.

Things are pretty cozy in the cab too, where Hunnel has a bed, a TV with VCR, another fax machine, a cellular phone with "speaker phone" capabilities that shut out the stereo, a police-band scanner, a choice of stereos and a CD system with 10-CD changer capabilities.

"I can listen to music for hours without changing a thing," says Hunnel.

"This is like driving a 74-foot-long Rolls Royce," he says with a grin. "Sure I can't convince you to become a driver?"