What 215/55R16 means
The inputs are 215 mm nominal section width, a 55-percent aspect ratio, and a 16-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 215 × 55 ÷ 100 = 118.25 mm. Adding two sidewalls to the 406.4 mm rim gives 642.9 mm (25.31 in) of nominal outside diameter.
A calculated reference
The 118.25 mm sidewall is identical to the geometric sidewall for 215/55R17. Only the rim term differs between those markings. A similar-looking size string can therefore conceal a full 25.4 mm diameter change.
Using a perfect-circle model, circumference is 2019.73 mm, equivalent to 495.12 revolutions per kilometer or 796.81 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 215/55R16, article 15576260000. 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