Mr. Tubbs, the nursing home roommate of A. J. Zander's grandfather, is a former cowboy too lively for his new surroundings--he's ""not a rocking chair kind of person."" To 16-year-old A.J., Mr. Tubbs is sort of an interesting character, but to 18-year-old Eloise Spence, a volunteer at the home, he's more of a hero. ""Spence"" cons A J. into a celebratory trip for Mr. Tubbs' hundredth birthday: a weekend jaunt to his former Flagstaff ranch. They sneak the old man out of the home and into a VW--three people, one basset hound, and a big, smelly saddle--and head out of Tucson. Their adventures on the road are well paced, and the story has many fine touches: a challenge to A.J.'s attitudes toward the elderly and doubts about his uncleared departure from home; a mild flirtation between the two teenagers; the recurrent minor demands of old man and frisky dog; discontinuities in Mr. Tubbs' memory and time sense; and the final irony--his ranch has become Happy Hacienda Ranch Estates. Not as exciting as Me, Cholay & Co.--Apache Warriors but as keenly crafted.