Experimental investigations were conducted to identify and quantify the noise mechanisms of individual elements of truck tire tread patterns. The element under study was handcarved into an otherwise blank tread, full-rubber-depth truck tire. The tire was mounted on the GMR Single Wheel Tire Noise Trailer and the noise radiated by the element was measured on-road as a function of position within the contact patch and tire speed using the two-microphone cross-spectral method of measuring acoustic intensity enhanced by position-triggered sampling. This report deals specifically with the noise mechanisms of cross groove type tread elements, which includes both individual cross groove and cross lug elements. The parameters investigated included groove depth, angle of the groove relative to the sidewall, groove shape, and spacing between grooves. In addition to a discussion of the noise mechanisms and the effects of the above parameters on radiated noise, several rather quiet cross groove and lug shapes found during the course of this work are also presented. Finally, several ideas and a procedure for designing quiet tread patterns in general are presented.