255/45R18 Tire Size Specifications & Compatible Vehicles
Overall Diameter
686.7 mm
Section Width
255 mm
Sidewall Height
114.8 mm
Circumference
2157.3 mm
Revs/Mile
746
Rim Diameter
18"
Inch Equivalent
27x10R18
Rim Width (ETRTO)
7.5" – 10.0"
Alternative Tire Sizes
These tire sizes are within 3% overall diameter of 255/45R18 and may be used as replacements:
Popular Comparisons
See how 255/45R18 compares to other common tire sizes:
Understanding 255/45R18
The tire size 255/45R18 means the tire has a section width of 255mm, an aspect ratio of 45% (the sidewall height is 45% of the width), and fits a 18-inch rim.
Sidewall Height = 255 x 0.45 = 114.8 mm
Overall Diameter = (114.8 x 2) + (18 x 25.4) = 686.7 mm
Circumference = 686.7 x π = 2157.3 mm
Overall Diameter = (114.8 x 2) + (18 x 25.4) = 686.7 mm
Circumference = 686.7 x π = 2157.3 mm
Frequently Asked Questions
The 255/45R18 is a standard tire size. Check your vehicle door jamb sticker or owner manual to confirm compatibility.
A 255/45R18 tire has an overall diameter of 686.7mm (27.0 inches). The sidewall height is 114.8mm, and the total circumference is 2157mm.
For 255/45R18 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 255/45R18 686.7mm diameter. Compatible alternatives include 255/50R17, 255/40R19, 165/85R16. Use our Tire Size Calculator to compare any two sizes.