Section Width225 mm (8.9")
Aspect Ratio308%
Rim Diameter18"
Overall Diameter1843 mm (72.6")
Sidewall Height693 mm
Circumference5791 mm
225/308R18 — Buy Tires

Everything to know about the 225/308R18 tire size

Size geometry

A 225/308R18 tire has a 225mm section width and a 308% aspect ratio, mounted on a 18-inch rim. Sidewall height works out to 693.0mm (27.28") and overall outside diameter is 1843.2mm (72.57"). At highway speed the tire completes about 173 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 225/308R18 is unavailable, the closest same-diameter substitutes on the same rim are 215/322R18 and 235/295R18. 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 225/308R18 you can upsize to 235/289R19 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 215/328R17 (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 225/308R18 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 225/308R18

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