What 175/65R15 means
The inputs are 175 mm nominal section width, a 65-percent aspect ratio, and a 15-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 175 × 65 ÷ 100 = 113.75 mm. Adding two sidewalls to the 381 mm rim gives 608.5 mm (23.96 in) of nominal outside diameter.
A calculated reference
Two 113.75 mm sidewalls supply 227.5 mm of the nominal diameter, while the 15-inch rim contributes 381 mm. The resulting 608.5 mm outside diameter is a different quantity from the rim measurement. A product and vehicle comparison still needs the complete wheel and service requirements.
Using a perfect-circle model, circumference is 1911.66 mm, equivalent to 523.11 revolutions per kilometer or 841.86 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 175/65R15, article 15575980000. 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