Pneumatic tire

A pneumatic tire suitable for mounting upon a rim having a pair of axially spaced apart annular mounting surfaces, with a predetermined nominal diameter, and a retaining flange adjacent to each mounting surface, said tire comprising a circumferentially extending tread portion having a maximum outside diameter at the mid-circumferential plane of the tire and a sidewall extending radially inwardly from each axial edge of the tread portion, a radial cross-section of the portion of said tire that is disposed radially outwardly of the retaining flanges of said rim when said tire is mounted upon said rim and inflated to its design inflation pressure, but not subjected to a load, having an external contour on each side of said mid-circumferential plane, exclusive of indicia on the sidewalls or traction elements of said tread portion, from said maximum outside diameter to the intersection of an external surface of each sidewall with a radially extending line that is tangent to the axially outer edge of the respective retaining flange that is substantially determined by the steps of:

• (a) drawing a first pair of straight lines, A and A.sup.1, both of which are perpendicular to the axis of rotation of said tire, line A being tangent to the axially outer extent of one of the retaining flanges of said rim and line A.sup.1 being tangent to the axially outer extent of the other retaining flange of said rim;
• (b) drawing a straight line B which is perpendicular to the axis of rotation of said tire and is located midway between lines A and A.sup.1 ;
• (c) striking a circle arc having a predetermined radius r with its center located on line B radially inwardly of the mounting surfaces of said rim, said circle arc being symmetrical with respect to line B and intersecting line B at a point located radially outwardly of said mounting surfaces a distance equal to one-half of the difference between the maximum outside diameter of the tread portion of the tire and the nominal diameter of said mounting surfaces, the end of said circle are located on the same side of line B as line A being point c, and the end of said circle are located on the same side of line B as line A.sup.1 being point c.sup.1, the axial distance between points c and c.sup.1 being no more than one-half of the axial distance between lines A and A.sup.1 ;
• and
• (d) locating a pair of points e,e.sup.1, one of the points e of said pair being located on line A and the other point e.sup.1 of said pair being located on line A.sup.1, said pair of points e,e.sup.1 being located radially outwardly of the radially outermost extent of said retaining flanges a distance no greater than one-half of the difference between the maximum outside diameter of the tread portion of the tire and the nominal diameter of mounting surfaces of the rim;
• and
• (e) drawing a pair of curved lines each of which at least approximates the curvature of an ellipse, one of said curved lines being tangent to the circle arc at point c and intersecting line A at point e, and the other curved line being tangent to the circle arc at point c.sup.1 and intersecting line A.sup.1 at point e.sup.1 ;
• and no point on the external surface of either sidewall is disposed axially outwardly of the axially outer extent of the respective retaining flange of said rim a distance greater than two percent of the axial distance between the axially outer extents of the retaining flanges of said rim.

The assembly of a pneumatic tire and a rim;

• said rim comprising a pair of axially spaced apart annular mounting surfaces with a predetermined nominal diameter, and a retaining flange adjacent to each mounting surface;
• said pneumatic tire comprising a circumferentially extending tread portion having a maximum outside diameter at the mid-circumferential plane of the tire and a sidewall extending radially inwardly from each axial edge of the tread portion to an annular bead porton, each bead portion being mounted upon one of the mounting surfaces of said rim and adjacent to the respective retaining flange, said tire being inflated to its design inflation pressure, but not subject to a load;
• a radial cross-section of the portion of said assembly that is disposed radially outwardly of the retaining flanges of said rim having an external contour on each side of said mid-circumferential plane, exclusive of indicia on the sidewalls or traction elements of said tread portion, from said maximum outside diameter to the intersection of an external surface of each sidewall with a radially extending line that is tangent to the axially outer edge of the respective retaining flange that is substantially determined by the steps of:
• (a) drawing a first pair of straight lines, A and A.sup.1, both of which are perpendicular to the axis of rotation of said tire, line A being tangent to the axially outer extent of one of the retaining flanges of said rim and line A.sup.1 being tangent to the axially outer extent of the other retaining flange of said rim;
• (b) drawing a straight line B which is perpendicular to the axis of rotation of said tire and is located midway between lines A and A.sup.1 ;
• (c) striking a circle arc having a predetermined radius r with its center located on line B radially inwardly of the mounting surfaces of said rim, said circle arc being symmetrical with respect to line B and intersecting line B at a point located radially outwardly of said mounting surfaces a distance equal to one-half of the difference between the maximum outside diameter of the tread portion of the tire and the nominal diameter of said mounting surfaces, the end of said circle arc located on the same side of line B as line A being point c, and the end of said circle arc located on the same line of line B as line A.sup.1 being point c.sup.1, the axial distance between points c and c.sup.1 being no more than one-half of the axial distance between lines A and A.sup.1 ;
• and
• (d) locating a pair of points e,e.sup.1, one of the points e of said pair being located on line A and the other point e.sup.1 of said pair being located on line A.sup.1, said pair of points e,e.sup.1 being located radially outwardly of the radially outermost extent of said retaining flanges a distance no greater than one-half of the difference between the maximum outside diameter of the tread portion of the tire and the nominal diameter of mounting surfaces of the rim;
• and
• (e) drawing a pair of curved lines each of which at least approximates the curvature of an ellipse, one of said curved lines being tangent to the circle arc at point c and intersecting line A at point e, and the other curved line being tangent to the circle arc at point c.sup.1 and intersecting line A.sup.1 at point e.sup.1 ;
• and no point on the external surface of either sidewall is disposed axially outwardly of the axially outer extent of the respective retaining flange of said rim a distance greater than two percent of the axial distance between the axially outer extents of the retaining flanges of said rim.