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Tire size

225/55R18 tire size: dimensions explained

Factory size on the Hyundai IONIQ 6. Below are the dimensions calculated from the size marking itself. Your vehicle's correct size, load index and speed rating are on the placard in the driver's door jamb; check it before buying.

MeasurementMetricImperial
Section width225 mm8.86 in
Sidewall height123.8 mm4.87 in
Overall diameter704.7 mm27.74 in
Wheel diameter457.2 mm18 in
Circumference2215 mm87.2 in
Revolutions per mile727

Calculated values: diameter = wheel + 2 × (width × aspect ratio). Real tires vary slightly by brand and model.

Reading the marking

225 is the section width in millimetres, 55 is the sidewall height as a percentage of that width, R means radial construction, and 18 is the wheel diameter in inches. A passenger (P or Euro-metric) tire and an LT tire in the same size are not interchangeable without checking load requirements.

Compare 225/55R18 with another size →

225/55R18 tires at Tire Rack

All-season

TireLoad/speedPrice per tire
Radar Dimax AS-8
Grand Touring All-Season		XL 102V$117.19View at Tire Rack
Nexen Aria AH7
Standard Touring All-Season		98T$118.86View at Tire Rack

Highway / touring

TireLoad/speedPrice per tire
Nexen N Priz RH7
Crossover/SUV Touring All-Season		98H$108.67View at Tire Rack
Advanta SVT Plus
Crossover/SUV Touring All-Season		98H$121.35View at Tire Rack

All-terrain

TireLoad/speedPrice per tire
Radar Renegade A/T Trail
On-Road All-Terrain		XL 102V$147.39View at Tire Rack
BFGoodrich Trail-Terrain T/A
On-Road All-Terrain		XL 102H$217.79View at Tire Rack

Summer performance

TireLoad/speedPrice per tire
Michelin Primacy 4
Grand Touring Summer		XL 102Y$160.12View at Tire Rack
Vredestein Ultrac
Ultra High Performance Summer		XL 102Y$172.34View at Tire Rack

Winter

TireLoad/speedPrice per tire
Goodyear WinterCommand
Studdable Winter/Snow		98T$165.21View at Tire Rack
Firestone Winterforce 2
Studdable Winter/Snow		98S$169.99View at Tire Rack

Showing the lowest-priced in-stock options in each category from 105 225/55R18 tires in Tire Rack's feed, sorted by price only. We don't rank by commission. Match or exceed the load index and speed rating on your placard.

Affiliate links: if you buy through a Tire Rack link, RightTread may earn a commission through CJ. It doesn't change your price. Prices are Tire Rack's per-tire prices from Tire Rack's product feed as of Nov 7, 2026, 10:23 PM PT. Prices change, so confirm on Tire Rack before you buy. Disclosure

Other sizes