What 215/50R17 means
The inputs are 215 mm nominal section width, a 50-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 × 50 ÷ 100 = 107.5 mm. Adding two sidewalls to the 431.8 mm rim gives 646.8 mm (25.46 in) of nominal outside diameter.
A calculated reference
This 50-percent marking has a sidewall exactly half its nominal width. The curated comparison with 225/50R17 increases nominal width and full diameter by the same 10 mm, because both rim size and the 50-percent ratio stay fixed.
Using a perfect-circle model, circumference is 2031.98 mm, equivalent to 492.13 revolutions per kilometer or 792.01 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 215/50R17, article 15577360000. 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