2.75-21: This indicates the tire's size.

• 2.75: This is the width of the tire in inches.
• 21: This denotes the diameter of the wheel rim in inches for which the tire is designed.

C858: This is likely a model or series designation assigned by the manufacturer. "C858" refers to the specific model of the tire.

4PR: This refers to the tire's ply rating, indicating the number of layers used in the tire's construction to enhance durability. "4PR" means the tire is constructed with 4 plies.

TT: "TT" stands for Tube Type. It indicates that the tire is designed to be used with an inner tube.