255/55R18 Tire Size Specifications & Compatible Vehicles

738mm140mmR18255/55R18Width: 255mm (10")
Overall Diameter
737.7 mm
Section Width
255 mm
Sidewall Height
140.3 mm
Circumference
2317.6 mm
Revs/Mile
694
Rim Diameter
18"

Compatible Vehicles

The following vehicles use 255/55R18 tires from the factory:

2025 Infiniti QX60 Pure 2024 Infiniti QX60 Pure 2023 Infiniti QX60 Pure 2022 Infiniti QX60 Pure

Alternative Tire Sizes

These tire sizes are within 3% overall diameter of 255/55R18 and may be used as replacements:

255/60R17 Safe  0.0% · same width · -1" rim 255/50R19 Safe  0.0% · same width · +1" rim 255/45R20 Safe  0.0% · same width · +2" rim 235/65R17 Safe  0.1% · -20mm · -1" rim 235/60R18 Safe  0.2% · -20mm · same rim 235/70R16 Safe  0.3% · -20mm · -2" rim 235/55R19 Safe  0.5% · -20mm · +1" rim 275/50R18 Safe  0.8% · +20mm · same rim 275/45R19 Safe  1.0% · +20mm · +1" rim 265/45R20 Safe  1.2% · +10mm · +2" rim 275/40R20 Safe  1.3% · +20mm · +2" rim 265/50R19 Safe  1.3% · +10mm · +1" rim

Understanding 255/55R18

The tire size 255/55R18 means the tire has a section width of 255mm, an aspect ratio of 55% (the sidewall height is 55% of the width), and fits a 18-inch rim.

Sidewall Height = 255 x 0.55 = 140.3 mm
Overall Diameter = (140.3 x 2) + (18 x 25.4) = 737.7 mm
Circumference = 737.7 x π = 2317.6 mm

With an aspect ratio of 55%, 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 255/55R18 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.