What 225/50R17 means
The inputs are 225 mm nominal section width, a 50-percent aspect ratio, and a 17-inch nominal rim diameter. The R identifies radial construction. The width is not a wheel-width measurement, and the rim number is not the outside diameter of the tire.
Nominal sidewall height is 225 × 50 ÷ 100 = 112.5 mm. Adding two sidewalls to the 431.8 mm rim gives 656.8 mm (25.86 in) of nominal outside diameter.
A calculated reference
The nominal sidewall is 112.5 mm. Compared with 215/55R17, this marking is wider but has a smaller diameter because its lower aspect ratio more than offsets the extra width. The relationship must be calculated, not guessed from the first number.
Using a perfect-circle model, circumference is 2063.4 mm, equivalent to 484.64 revolutions per kilometer or 779.95 per mile. These are derived from unrounded diameter; actual rolling circumference also depends on the product and operating conditions.
Source and scope
General Tire’s AltiMAX RT45 source includes 225/50R17, article 15576380000. It was checked on October 27, 2026. That record verifies the published marking used here; it does not turn these calculated dimensions into that product’s measured specification or establish availability.
Use the exact product and vehicle requirements for load and speed ratings, permitted rim dimensions, inflation and clearance. Nominal geometry alone cannot verify fitment, braking behavior, handling or safety.
Sources and further reading
- AltiMAX RT45 — General Tire
- Tire Markings Explained — Michelin
- Tire glossary — Michelin