Power King Premium Trailer ST225/75D15 Tires
Power King Premium Trailer ST225/75D15 D 113/108L is a trailer tire.
Power King Premium Trailer ST225/75D15 D 113/108L Tire Specs
ST225/75D15 is a Special Trailer tire. It also comes in a LT-Metric (LT225/75R15), a Metric (225/75R15) and a P-Metric (P225/75R15) variant
Let us decode each aspect of the tire size code to have a full understanding what this tire size means.
ST indicates that ST225/75D15 is a trailer tire.
225 is a section width of the tire from one sidewall to the other. Tire tread width is typically a bit narrower than the section width. Section width of ST225/75D15 tire is 225 millimeters.
75 represents the aspect ratio of a tire, which is a ratio of the tire's sidewall height to its width. For ST225/75D15 tire, the sidewall height is 75% of its tread width.
D denotes that ST225/75D15 tire has diagonal bias construction.
15 represents the wheel diameter in inches that the tire is designed to fit. ST225/75D15 can be mounted on rims with 15 inches in diameter.
D denotes the load range of a tire. Load Range D is equivalent to an 8-ply rating in the old system, but the actual number of plies in the tire may be different. These tires are generally rated for a maximum inflation pressure of 65 psi, and are commonly found on light trucks, SUVs, and trailers, where higher load carrying capacity is needed. They are particularly important for vehicles that are used for towing or carrying heavy loads.
113/108 indicates a dual load index, meaning a tire can be used in a single or a dual application. For a single application, load index of 113 can support a maximum load of 2535 pounds or 1150 kilograms per tire. For a dual application, load index of 108 can support a maximum load of 2205 pounds or 1000 kilograms per tire.
L indicates the speed rating. A tire with a speed rating of L is approved for speeds up to 75 miles per hour or 121 kilometers per hour under optimal conditions.
Tire manufacturer part number (MPN) is STB51.

ST225/75D15 Dimensions Chart
Power King Premium Trailer ST225/75D15 tire has a diameter of 28.3", a width of 8.9", mounts on a 15" rim, and makes 713 revolutions per mile.
Metric | Inches | |
---|---|---|
Tire Width | 225 mm | 8.9" |
Aspect Ratio | 75% | |
Rim Diameter | 381 mm | 15" |
Tire Diameter | 719 mm | 28.3" |
Sidewall Height | 169 mm | 6.7" |
Circumference | 2258 mm | 88.9" |
Revolutions | 443 per km | 713 per mile |
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