Isostable tubular tire

A tubular tire for motor vehicles of the type including an inflatable inner tube, a casing of the radial type, a reinforcement in addition to the casing in the ground contacting area, a rim strip, some rubber sides, a tire tread and two semi-rigid circular rods set at the level of the reinforcement at the edges thereof characterized by the fact that the rim strip has a width included between approximately 0.25 L and approximately 0.35 L, wherein L represents the total width of the tire tread, by the fact that the transverse section of the tire has in a known manner an H over L ratio which is included between 0.5 and 0.6 wherein H represents the total height between the rim strip and the tire tread, and by the fact that seen in transverse section each side of the tire has a profile corresponding to a curve described by the equation:

• ##EQU2## which is substantially included between two points wherein the tangents are respectively vertical at y approximately equal to b and horizontal at y approximately equal to a, said approximately horizontal point of tangency corresponding substantially with the intersection of the tire vertical section centerline and the rim and said vertical point of tangency corresponding substantially with the outermost maximum cross-section width of the tire, the aggregate being such that the tire when seen in transverse section forms an isostable system.