225/40R18 Tire Size Specifications & Compatible Vehicles
Compatible Vehicles
The following vehicles use 225/40R18 tires from the factory:
Alternative Tire Sizes
These tire sizes are within 3% overall diameter of 225/40R18 and may be used as replacements:
Popular Comparisons
See how 225/40R18 compares to other common tire sizes:
Understanding 225/40R18
The tire size 225/40R18 means the tire has a section width of 225mm, an aspect ratio of 40% (the sidewall height is 40% of the width), and fits a 18-inch rim.
Overall Diameter = (90.0 x 2) + (18 x 25.4) = 637.2 mm
Circumference = 637.2 x π = 2001.8 mm
With an aspect ratio of 40%, this is a low-profile tire. Low-profile tires offer sharper steering response and better cornering stability, but provide a firmer ride and are more susceptible to pothole damage. They are commonly found on sport sedans and performance vehicles.
Choosing Replacement Tires
When replacing 225/40R18 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.