1. Size designation in inches or mm; here: 315 = nominal width in mm;
80 = aspect ratio in % (Aspect height/Aspect width), R = radial tyre, 22.5 = rim diameter in inches.
2. Nominal operating code. This is made up of the load symbol for single and twin tyre fitments and the speed symbol for the reference speed. 154 means 3.750 kg per tyre as a single tyre fitment and 150 means 3.350 kg per tyre in dual fitment. M stands for a max. speed of 130 km/h.
3. Additional service description. On tyres which are suitable for a variety of applications (e.g. on trucks and buses), the permitted load can be increased and the maximum speed reduced, or vice versa. An additional load index is then given for single/twin tyre fitments and a letter for the appropriate reference speed. The additional service description is encircled.
4. Ply rating: Refers to the load capacity type. On crossply tyres this is used to indicate the number of plies in the casing. Today this reference no longer indicates the actual number of plies on a tyre and is not even included in the labelling on newer tyre types.
5. Designates tubeless tyres.
6. Designates regroovable tyres.
7. Refers to the six treadwear indicators in the base of the tread pattern.