2.75 is the width in millimetres of the tyres cross section.
Radial construction. R stands for radial-ply construction.
18 inches, stands for the diameter of the wheel that the tyre is designed to fit.
- Load Rating46
46 (170 kg) is the load index i.e. the maximum weight each tyre can carry at full speed.
- Speed RatingP
P (150 kmph) is the speed rating i.e. the maximum speed for the tyre at full load.