Patent ID: 6491077
Filing Date: 2002-12-10
Classification: B60C,Y10T

Abstract:
A tire, with a form ration H/S between 0.3 and 0.8, comprising a carcass reinforcement (1) of equatorial radius RSSÂ±&Dgr;RSS, where &Dgr;RSS is equal to 1 times the minimum thickness of said carcass reinforcement, covered radially by a crown reinforcement (3) which is essentially quasi-cylindrical, formed of at least one working ply (30) of circumferential reinforcement elements, said carcass reinforcement (1) on each side of the equatorial plane XXâ€², on the one hand being tangential to a circle C termed the holding circle, the common tangent to the said circle C and to the meridian profile of the carcass reinforcement (1) making an angle &agr;, open axially towards the outside and radially towards the inside, between 20Â° and âˆ’80Â° at the tangency point T between said profile and the holding circle C and with respect to a line parallel to the rotation axis and passing through said tangency point T, and on the other hand, in its portion located between said tangency point T and the point E of greatest axial width, being provided with a reinforcement armature (6) of circumferentially non-extensible elements, the tire characterized in that when viewed in meridian section and when the tire is fitted on its working rim and inflated to the recommended pressure, the centerline of each half of the main portion of the carcass reinforcement (1) has a meridian profile which consists of four circular arcs:a first circular arc TA of radium râ€²1, comprised between or equal to the values r1 and/or 2r1, which is on the one hand tangential to the holding circle C, concentric with the rim edge of radius rj, positioned radially above and separated from said edge by a distance eT at least equal to twice the minimum thickness of the carcass reinforcement, and which, on the other hand, has a point of intersection A with a second circular arc AE of radius râ€³1, comprised between the values r1 and 2r1, which is tangential to the line D perpendicular to the rotation axis passing through the point E of greatest axial width, a third circular arc EF of radius r2, which is tangential to the second circular arc AE at the point E of greatest axial width and also tangential to a fourth circular arc FG parallel to the quasi-cylindrical crown reinforcement (3), at a point F separated by a distance d from the line parallel to the rotation axis and passing through the center OJ of the holding circle C, such that the quantities d, r1 and r2 satisfy the relationships: d=r2 +(r1âˆ’arj+et)cos &agr;and r1=r2 RSS/(RSSâˆ’r2) â€ƒwhere &agr; is the angle between the tangent at T and a line parallel to the rotation axis, and a is a constant which can have the values âˆ’1,0 or +1, a fourth circular arc FG, a radius of RTC equal to the transverse radius of RT of the crown reinforcement reduced by at most the minimum thickness of the carcass reinforcement, the tire further characterized in that the width of the working crown reinforcement (3), which is the larger of the axial width of the narrowest ply of circumferential reinforcement elements and the axial width of the narrowest of any plies of inclined reinforcement elements, is comprised between the distance separating the two tangency points F of said meridian profile to the crown reinforcement (3) and said distance increased by 2r2/3.