About the 225/45R18 Tire

The 225/45R18 is a common tire size for midsize sedans such as Toyota Camry, Honda Accord, and Hyundai Sonata.

With a 101.3 mm sidewall (45% aspect ratio), this tire offers a balanced blend of ride comfort and handling precision — versatile for both city driving and spirited cornering.

Compared to the baseline 235/45R18, this tire's overall diameter differs by -1.3% — a speedometer calibrated for 235/45R18 would read 101.4 km/h at an actual 100 km/h.

OE on the BMW 3 Series (F30 M-Sport), BMW 2 Series (G42), Audi A4 (B8/B9 18" packages), Mercedes-Benz C-Class (W204/W205 Sport) and Mercedes A-Class (W177). Load index 91W or 95Y reinforced. Together with 225/40R18, the most-stocked premium-sedan replacement size in the US northeast and Europe.

Mainstream sedan sizes balance compound longevity against light all-season handling. When replacing, match the OE speed rating (H or V on most trims) — installing a lower rating voids many manufacturer load-test certifications and is illegal on autobahn-rated vehicles. Wheel-well clearance is rarely a concern at this rim diameter; speedometer drift across factory alternatives stays well inside the ±3% legal window.

Tire Measurements

Tire Code225/45R18
Section Width225 mm
Aspect Ratio45%
Rim Diameter18"
Sidewall Height101.3 mm
Overall Diameter659.7 mm / 25.97"
Circumference2072.5 mm / 81.59"
Revolutions per km482.5
Revolutions per mile776.5

Adjacent Size Comparison

Tire Code OD (mm)Δ mmΔ % Speedo at 100 km/h
225/45R17 634.3 -25.4 -3.9% 104.0
225/40R18 637.2 -22.5 -3.4% 103.5
215/45R18 650.7 -9.0 -1.4% 101.4
225/45R18 (current) 659.7 100.0
235/45R18 668.7 +9.0 +1.4% 98.7

Frequently Asked Questions

What is the overall diameter of a 225/45R18 tire?
The overall diameter is 659.7 mm (25.97 in), with a 101.3 mm sidewall on a 18-inch rim.
How many revolutions per kilometer does a 225/45R18 tire make?
It makes 482.5 revolutions per kilometer, with a circumference of 2072.5 mm.
What vehicles commonly use 225/45R18 tires?
The 225/45R18 is standard OEM equipment on midsize sedans such as Toyota Camry, Honda Accord, and Hyundai Sonata. Always check your owner's manual or door placard before switching sizes.

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