255/40R18 Tire Size Specifications & Compatible Vehicles
Overall Diameter
661.2 mm
Section Width
255 mm
Sidewall Height
102.0 mm
Circumference
2077.2 mm
Revs/Mile
775
Rim Diameter
18"
Inch Equivalent
26x10R18
Rim Width (ETRTO)
7.5" – 10.0"
Compatible Vehicles
The following vehicles use 255/40R18 tires from the factory:
Alternative Tire Sizes
These tire sizes are within 3% overall diameter of 255/40R18 and may be used as replacements:
Understanding 255/40R18
The tire size 255/40R18 means the tire has a section width of 255mm, an aspect ratio of 40% (the sidewall height is 40% of the width), and fits a 18-inch rim.
Sidewall Height = 255 x 0.4 = 102.0 mm
Overall Diameter = (102.0 x 2) + (18 x 25.4) = 661.2 mm
Circumference = 661.2 x π = 2077.2 mm
Overall Diameter = (102.0 x 2) + (18 x 25.4) = 661.2 mm
Circumference = 661.2 x π = 2077.2 mm
Frequently Asked Questions
The 255/40R18 tire size is used on 8 vehicle trims including the 2025 BMW 3 Series, 2025 BMW 3 Series, 2024 BMW 3 Series and 5 more.
A 255/40R18 tire has an overall diameter of 661.2mm (26.0 inches). The sidewall height is 102.0mm, and the total circumference is 2077mm.
For 255/40R18 tires, the ETRTO recommended rim width is 8.5". The acceptable range is 7.5" minimum to 10.0" maximum. Using a rim outside this range can cause improper bead seating and unsafe handling.
Yes, as long as the replacement tire overall diameter is within 3% of the 255/40R18 661.2mm diameter. Compatible alternatives include 255/45R17, 255/35R19, 255/50R16. Use our Tire Size Calculator to compare any two sizes.