275/50R18 Tire Size Specifications & Compatible Vehicles

Overall Diameter

732.2 mm

Section Width

275 mm

Sidewall Height

137.5 mm

Circumference

2300.3 mm

Revs/Mile

700

Rim Diameter

18"

Alternative Tire Sizes

These tire sizes are within 3% overall diameter of 275/50R18 and may be used as replacements:

275/45R19 Safe 0.3% · same width · +1" rim 285/40R20 Safe 0.5% · +10mm · +2" rim 275/40R20 Safe 0.6% · same width · +2" rim 255/45R20 Safe 0.7% · -20mm · +2" rim 255/50R19 Safe 0.7% · -20mm · +1" rim 255/55R18 Safe 0.8% · -20mm · same rim 255/60R17 Safe 0.8% · -20mm · -1" rim 285/45R19 Safe 0.9% · +10mm · +1" rim 265/55R17 Safe 1.2% · -10mm · -1" rim 265/50R18 Safe 1.4% · -10mm · same rim 265/45R19 Caution 1.5% · -10mm · +1" rim 295/40R20 Caution 1.6% · +20mm · +2" rim

Understanding 275/50R18

The tire size 275/50R18 means the tire has a section width of 275mm, an aspect ratio of 50% (the sidewall height is 50% of the width), and fits a 18-inch rim.

Sidewall Height = 275 x 0.5 = 137.5 mm
Overall Diameter = (137.5 x 2) + (18 x 25.4) = 732.2 mm
Circumference = 732.2 x π = 2300.3 mm

With an aspect ratio of 50%, this is a standard-profile tire that balances ride comfort with handling precision. This profile range is the most common for passenger cars, crossovers, and light SUVs.

Choosing Replacement Tires

When replacing 275/50R18 tires, verify the size matches your vehicle's tire placard (typically found on the driver's door jamb or in the owner's manual). The NHTSA Tire Ratings Search tool lets you look up manufacturer load and speed ratings for specific tires.

Key factors beyond size: load index (must meet or exceed the vehicle's requirement), speed rating (must match or exceed the original specification), and seasonal type (all-season, summer, or winter) based on your driving conditions. The U.S. Tire Manufacturers Association recommends replacing all four tires at once, or at minimum in pairs on the same axle.