What 205/65R15 means
The inputs are 205 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 205 × 65 ÷ 100 = 133.25 mm. Adding two sidewalls to the 381 mm rim gives 647.5 mm (25.49 in) of nominal outside diameter.
A calculated reference
At this 65-percent ratio, increasing nominal width by 10 mm changes total diameter by 13 mm when the rim is fixed. The comparison with 195/65R15 demonstrates that relationship with a separate percentage based on the chosen original.
Using a perfect-circle model, circumference is 2034.18 mm, equivalent to 491.6 revolutions per kilometer or 791.15 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 205/65R15, article 15576200000. 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