Abstract: A radial pneumatic light truck or automobile tire 40 having a tread 42 is described. The tread 42 has a base 43, a plurality of traction elements 52 extending radially outwardly from the base 43 and at least one circumferentially continuous wide groove 54,55. The wide groove 54,55 has a circumferentially continuous window 72 extending from the tread base 43 to the radially outer contacting surface 53. The window 72, when viewed in the ground contacting portion of the tread 42, has a shape that is triangular or trapezoidal having two sides 73,74 and a radially outer long base 75. The long base 75 has an axial width of 7% to 20% of the tread width. The wide groove 54,55 has a zig-zag portion 70 extending radially from the tread base 43 in a circumferentially continuous path. The sides 73,74 of the window 72 define the maximum axial extent or amplitude of the zig-zag portion 70 into the wide groove 54,55.