The present invention is related to a demountable tire rim (1) with a spare inner wheel (3) with antifriction systems which allow running with tubeless tires, without their deterioration; the demountable tire rim (1) comprises two complementary annular parts (4)(5) provided with reciprocal threaded coupling means (10). The body of the demountable tire (1) comprises two complementary annular parts (4)(5) which consist of a first part (4) and a second part (5). Both complementary annular parts (4)(5) are provided with each side holding rims (6) (13) for the tire (2). The modifications of the tires (2) have the purpose of adapting them to run under flat condition and determine a guided movement on it, and in relation to the tire rim, it decreases the rotating displacement on it.