Dunlop AT 20 Grand Trek 265/65 R17 110S

S

S is the speed rating i.e. the maximum speed for the tyre at full load.

265

265 is the width in millimetres of the tyres cross section.

65

65 is the Aspect Ratio, it is the ratio of the sidewall height to the cross section width.

17

17 inches, stands for the diameter of the wheel that the tyre is designed to fit.

R

Radial construction.R stands for radial-ply construction.