Section Width325 mm (12.8")
Aspect Ratio45%
Rim Diameter18"
Overall Diameter750 mm (29.5")
Sidewall Height146 mm
Circumference2355 mm
325/45R18 — Buy Tires

Everything to know about the 325/45R18 tire size

Size geometry

A 325/45R18 tire has a 325mm section width and a 45% aspect ratio, mounted on a 18-inch rim. Sidewall height works out to 146.3mm (5.76") and overall outside diameter is 749.7mm (29.52"). At highway speed the tire completes about 425 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 325/45R18 is unavailable, the closest same-diameter substitutes on the same rim are 315/46R18 and 335/44R18. Both keep your speedometer reading within 1% — safe for daily use, ABS, and stability control. Always verify load and speed ratings before swapping.

Plus / minus sizing options

For a 325/45R18 you can upsize to 335/40R19 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 315/50R17 (minus-one) for a softer ride or winter setup. Both stay inside the Âą3% diameter tolerance that ABS and TPMS systems expect.

Vehicle compatibility

0 vehicles in our database run the 325/45R18 tire size from the factory. Aftermarket fitment depends on rim width, offset, and clearance — match these specs to your wheel before purchasing tires.

Vehicles Using 325/45R18

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