The Tubes, a San Francisco-based rock-theater group, have inhabited the outer fringes of the rock world for several years. Their madness is inspired, their exaggeration calculated; and their stage-shows employ sophisticated musical passages and imaginative theatrics to present a chaotic and sardonic view of the absurdities of contemporary life.

Rock theater is a sub-genre of rock music that first appeared in the late '60s with such English groups as The Who and The Crazy World of Arthur Brown. Since these first innovative efforts, the form has taken two main directions - from the sophisticated structure and story-line of rock operas like "Tommy" to the sophomoric use of theatrical devices by such groups as Kiss, in which the devices are used merely as random elements in a "rock show." The Tubes - who will appear Friday night at the Warner Theater - represent a meeting of these extremes, in which various tableaux are presented as a "show," but also create a sustained image of the decadence of modern culture.

Their new record, "Live" (A&M SP-6003) was recorded at a concert in London in November 1977 and captures the strange and compelling quality of their music. The photos on the inner cover suggest the outlandish and satiric nature of their theatrics.

From the music and photos, it is obvious that the world, as The Tubes see it, is nothing more than an X-rated Japanese sci-fi flick, directed by Monty Hall as a sort of primal-tribal TV game show. Dancers, dressed in the full sadomasochistic garb, parade across the stage along with spacy villains and Cary Grant characters, to a backdrop of swirling lights and TV sets that transmit the stage action. Add to this song titles such as "Don't Touch Me There" and "Mondo Bondage," and you get the idea that either The Tubes are absolutely crazy, or that they think everyone else is.

It would be very easy to dismiss this group as a slick commercial package, another decadent rock show unloaded on an already decadent rock market. This would be a mistake however, for The Tubes are highly skilled musicians who blend complex musical sections with satiric lyrics and dialogue to a degree that has not been attained since the departure of the Bonzo Dog Band (early English pioneers of rock comedy and satire).

Many groups have tried this format and failed, from a lack of either musical or comedic skill. The Tubes succeed at both. "What Do You Want From Life" is a brilliant portrayal of materialism that ends with the lead singer going out into the crowd and playing a grotesque version of "Let's Make A Deal." The group chants the title as the singer offers the "contestant" such prizes as the world's biggest safety pin from Johnny Rotten of the Sex Pistols, and ends by offering "a poke in the eye with a blunt stick." "Stand Up and Shout" is introduced with the lead singer impersonating an obnoxious Cockney drunk and the announcer apologizing by saying, "Ever since he became a star. . . ."

The eclecticism of the stage show is mirrored in the musical sections. The jazz-based "Overture" is countered by the heavy rocker, "White Punks On Dope"; while "Got Yourself a Deal" features a blending of the styles and even includes a mock-Chuck Berry guitar break. The songs are tightly written with little improvisation and a dynamic flair that heightens the sense of theater. The instruments are orchestraed to a far greater degree than most rock groups; the musical sounds seem carefully selected to express the diverse moods of the individual songs; and the compositions, while not particularly impressive by themselves, are perfectly suited to the needs of the show as a unified structure.

(The one lapse in taste and quality is the "Crime Medley," in which the theme songs from old TV series are played. The campiness of this selection is one notable failure of the record.)

Rock theater has a long way to go as an artistic form. Almost all productions rely on satire and comedy because they lend themselves most readily to the medium. But such subjects are not easily produced, and the work of The Tubes is a promising first step.