215/55R17 vs 225/50R18 tire size comparison

Change either size and everything below updates.

Start from your car make, model, year

Make Model Year

Width/AspectRRim

DiameterxWidthRRim

Width/AspectRRim

DiameterxWidthRRim

Width in mm · aspect = sidewall height as a % of width · rim in inches

Flotation (LT) sizes, all in inches: overall diameter × section width, then rim

Within the usual 3% rule

+2.08% diameter

Most fitment guides accept up to 3%. Check clearance at full lock and full suspension compression before committing.

Needs 18″ wheels: this tire does not fit your 17″ rims.
10 mm wider: check inner clearance and that your rims are wide enough.

Tires in 225/50R18

Check price on Amazon · 225/50R18 Best-rated 225/50R18 tires

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Measurement	215/55R17	225/50R18	Diff	%
Overall diameter	26.31″668 mm	26.86″682 mm	+0.55″	+2.1%
Section width	215.0 mm	225.0 mm	+10.0 mm	+4.7%
Sidewall height	118.3 mm	112.5 mm	−5.8 mm	−4.9%
Rim diameter	17″	18″	+1″	+5.9%
Circumference	82.66″2100 mm	84.38″2143 mm	+1.72″	+2.1%
Revolutions per mileturns per distance; drives the odometer	767476 /km	751467 /km	−16	−2.0%
Ride height change	—	—	+0.27″ +6.9 mm

Speedometer reading

Speedo shows

60mph

97 km/h

Actual speed

61.2mph

99 km/h

Overlay

215/55R17225/50R18

How to use the tire size calculator

Put your current tire size — width, aspect ratio and rim diameter — into the first form, then your desired size into the second. You’ll get the difference between the new and the old size, plus the speedometer reading difference and your actual speed on the new set. Both metric and flotation (LT inch) sizes are supported.

The calculator helps you decide whether a set of tires and wheels will fit your car. To compare tires by brand and model instead, use our tire comparison tool; to look up factory sizes, browse by car make.