to put the whole nitto quality issue in perspective...i have a groove as deep as the regular tread grooves in one of my SIDEWALLS! the back left tire has been hitting the blade on the inner fender where i had them cut and so over time a gash has been cut into the sidewall and most of the outer tread blocks are hanging off or have already been completely chopped off. so this extra tread groove is in the sidewall and the tire is still in one piece (well, technically one piece)