What 195/65R15 means
The inputs are 195 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 195 × 65 ÷ 100 = 126.75 mm. Adding two sidewalls to the 381 mm rim gives 634.5 mm (24.98 in) of nominal outside diameter.
A calculated reference
The curated comparison with 205/55R16 shows how a larger rim can coexist with a slightly smaller overall diameter. The other same-rim comparisons isolate width changes, so this page can serve as a useful baseline for more than one kind of calculation.
Using a perfect-circle model, circumference is 1993.34 mm, equivalent to 501.67 revolutions per kilometer or 807.36 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 195/65R15, article 15576140000. 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