Radial agricultural tire with a pitched tread

The present invention relates to an agricultural tire (10) having a casing (12) with a radial ply carcass (14) and an annular tread (40) having two sets (48,50) of lugs (44). The tire (10) has a greatly reduced lug vibration. The tread (10) is divided into a plurality of circumferentially repeating design cycles of at least two, preferably three distinct design cycle lengths. The circumferentially adjacent lugs (44) of the opposite set are offset by at least one design cycle. When the pitch ratio variance of the design cycles is at least 1.1 from small length (S) to large length (L), preferably 1.25 a reduction in lug induced vibration of 30% or more is possible. The lugs 44 preferably have a lug width (W), (W) being proportional to the length of the design cycle in which a majority of the lug lies. This effectively balances the mass of tread rubber around the periphery of the tire.