Section Width205 mm (8.1")
Aspect Ratio30%
Rim Diameter18"
Overall Diameter580 mm (22.8")
Sidewall Height62 mm
Circumference1823 mm
205/30R18 — Buy Tires

Everything to know about the 205/30R18 tire size

Size geometry

A 205/30R18 tire has a 205mm section width and a 30% aspect ratio, mounted on a 18-inch rim. Sidewall height works out to 61.5mm (2.42") and overall outside diameter is 580.2mm (22.84"). At highway speed the tire completes about 549 revolutions per kilometre — your speedometer and odometer were calibrated against this number.

Direct substitute sizes

If 205/30R18 is unavailable, the closest same-diameter substitutes on the same rim are 195/32R18 and 215/29R18. 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 205/30R18 you can upsize to 215/23R19 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 195/38R17 (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 205/30R18 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 205/30R18

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