The 14.00r20 Michelin XZL tires on my M923A2 are about 15 years old. They have 80+% tread. However, there are a number of small cracks in the side wall, presumably due to age, UV, etc. Are these tires safe to run or do they need to be replaced? (Note: The photos below are highly zoomed as you can see from the comparison to the text on the tire).