Underground mine tire

An underground mine tire having a nominal bead diameter of 20 inches or less comprises:

• a pair of annular bead cores;
• a steel cord reinforced radial carcass ply wrapped around the bed cores having a ply turnup end located between 40% and 60% of the section height of the tire;
• a belt reinforcing structure having a radially inner first belt layer, a second belt layer, a third belt layer;
• a pair of rubber sidewalls, each rubber sidewall extending from a bead to the tread along the outer periphery of the carcass ply and having minimum thickness of 0.5 inches, wherein the first, second and third belt layers have wires having a diameter of 0.06 inches or greater spaced at 8 ends per inch or less and the radially outermost fourth layer has wire having a diameter of 0.04 inches or less spaced at 12 ends per inch or more.

A method of increasing the load carrying capacity of a radial tire comprising the steps of:

• determining a maximum load, x+y;
• providing a mold for a radial tire capable of molding a tire having a rated load x;
• adding a spacer between adjacent mold halves thereby increasing the axial width of the mold to achieve the rated load x+y;
• designing an unvulcanized tire having a belt reinforcing structure and a radial ply by increasing the belt width and ply width of the tire and applying sidewall rubber to maintain a ply path curvature;
• and
• molding the tire.