225/65R17 is a tire size code that indicates the tire's width, aspect ratio, construction, and diameter. 225 means the tire's width is 225 millimeters. 65 represents the tire's aspect ratio of 65%, the ratio of height to width. R means the tire's construction is radial, the most common type. 17 indicates the tire's diameter is 17 inches, which is the size of the wheel rim.  All-season means the tire can perform in all weather conditions, from dry and wet roads to light snow.