Pneumatic tractor tire

A pneumatic tire for tractors and like vehicles comprising a ground surface-engaging tread portion surrounding a reinforcing carcass, said tread portion comprising:

• (a) a first set of long lugs and a first set of short lugs alternately disposed about the circumferential periphery of the tread, each lug of said first set of long and short lugs emanating from the same lateral edge of said tread and extending axially inward therefrom, the spacing of said alternately disposed lugs about said circumferential periphery of the tread being such that void space exists in the tread between each alternating lug, the emanation point of each long or short lug along the lateral tread edge being substantially equally spaced apart along said lateral edge from the emanation point of the next alternating lug;
• (b) a second set of long lugs and a second set of short lugs being identical to said first set of long lugs and said first set of short lugs but opposite in hand, alternately disposed about the circumferential periphery of the tread and emanating from the other lateral edge of said tread and extending axially inward therefrom, the alternating circumferential disposition of said second set of long lugs and said second set of short lugs being offset relative to the disposition of said first set of long lugs and said first set of short lugs such that, across the tread width, an emanating point for a short lug along one lateral tread edge is substantially directly opposite an emanating point for a long lug along the other lateral tread edge;
• wherein (i) each said lug has a leading edge and a trailing edge (ii) each said lug is smoothly curved along its length from its emanating point at a tread edge to its terminating point axially inward thereof, the direction of axially inward curvature being in the direction of intended tire rotation;
• (iii) the radius of curvature from the leading edge of each long lug and the leading edge of each short lug are substantially the same, the radius of curvature of the trailing edge of each long lug and the trailing edge of each short lug are substantially the same, and the radius of curvature of said trailing edge is greater than that of said leading edge;
• (iv) each said long lug terminates axially inward a short distance across the tread centerline and each said short lug terminates axially inward a short distance before said centerline;
• and (v) for a point along the length of the trailing edge of said lugs, the curvature angle formed between a line tangent to said point and a line, through said point, perpendicular to the centerline, increases as said point progresses axially inward.