Front tires on my old 3320 airdrill have some white showing between the raised lugs on the front implement tires. Seems the stubble stabs in the groove and peels off the very thin layer of black that is over the white cords. I have been replacing these tires every time that I see white, but the rest of the tire looks good. Tires are so expensive that I am wondering if the tires will last once the white shows up in the recessed grooves on the face of the tire? Seems to only take 1 season before the stubble causes the white to show on the tires. Should last more than 1 year, but I hate breakdowns.