What 215/45R17 means
The inputs are 215 mm nominal section width, a 45-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 215 × 45 ÷ 100 = 96.75 mm. Adding two sidewalls to the 431.8 mm rim gives 625.3 mm (24.62 in) of nominal outside diameter.
A calculated reference
The 96.75 mm nominal sidewall is below 100 mm even though the width is 215 mm. Increasing width to 225 mm while retaining the 45-percent ratio would add 4.5 mm per sidewall. The editable tool can explore that example; a fixed comparison page is not published for this marking.
Using a perfect-circle model, circumference is 1964.44 mm, equivalent to 509.05 revolutions per kilometer or 819.24 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 215/45R17, article 15577350000. 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