Which of the following is not a tire problem to check for and avoid?

During an inspection, there are a number of tire problems to check for and avoid. Look for air pressure that is too low or too high; excessive wear; cuts or other damage; tread separation; dual tires that come into contact with each other or other parts of the vehicle; mismatched tire sizes; radial and bias-ply tires used together; cut or cracked valve stems; and regrooved, recapped, or retreaded tires on the front wheels of a school bus.