225/55R18 tire size
A 225/55R18 tire is 225 mm wide with a 123.8 mm sidewall, 55% of the width, on a 18-inch rim, which puts the whole tire at 704.7 mm, or about 27.7 inches, tall. No model in our data leaves the factory on it, but it can replace the original size on 9 models within 3% of the height.
Overall height
704.7 mm
27.7 in
Sidewall
123.8 mm
55%
Circumference
2,214 mm
Revs per km
452
Actual dimensions of 225/55R18
| Section width | 225 mm (8.9 in) |
| Sidewall height | 123.8 mm (4.87 in) |
| Rim diameter | 18 in (457.2 mm) |
| Overall diameter | 704.7 mm (27.7 in) |
| Circumference | 2,214 mm |
| Revolutions per km | 452 |
| Inch notation (height x width) | 27.7x8.9R18 |
Worked out: sidewall 225 x 0.55 = 123.75 mm, rim 18 x 25.4 = 457.2 mm, overall 457.2 + (123.75 x 2) = 704.7 mm, circumference 3.1416 x 704.7 = 2,214 mm. One turn of the tire moves the car about 2.21 m, which is 452 turns per kilometer. New to sidewall codes? See how to read a tire size.
These are nominal figures from the standard formula. Real tires vary slightly by brand and squat a little under the weight of the car.
Cars fitted with 225/55R18 from the factory
No model sold in Thailand in our data leaves the factory on 225/55R18.
Cars that can switch to 225/55R18
These cars leave the factory on another size within 3% of the height of 225/55R18. Whether it fits still depends on rim width and wheel-well clearance.
| Model | Factory size | Height difference | Wheel |
|---|---|---|---|
| Toyota Yaris Cross HEV2023–present | 215/55R18 | +1.59% | Same wheel |
| Mazda CX-302020–present | 215/55R18 | +1.59% | Same wheel |
| BYD ATTO 32022–present | 215/55R18 | +1.59% | Same wheel |
| MG HS / HS PHEVCurrent model | 235/50R18 | +1.81% | Same wheel |
| BYD Seal2023–present | 235/45R19 | +1.53% | Needs 18-inch wheels |
| Toyota C-HR2018–2023 | 215/60R17 | +2.16% | Needs 18-inch wheels |
| Toyota Corolla Cross2020–present | 215/60R17 | +2.16% | Needs 18-inch wheels |
| Honda HR-V e:HEV2022–present | 215/60R17 | +2.16% | Needs 18-inch wheels |
| Mazda CX-52017–present | 225/65R17 | −2.71% | Needs 18-inch wheels |
Sizes that can replace 225/55R18
Sizes within ±3% of the overall height of 225/55R18. “At 100 km/h” is the real speed when the speedometer reads 100.
| Size | Height | Difference | At 100 km/h | Sidewall | Match | Compare |
|---|---|---|---|---|---|---|
| 245/40R20 | 704.0 mm | −0.7 mm (−0.10%) | 99.9 km/h | 98.0 mm | Very close | Compare |
| 245/45R19 | 703.1 mm | −1.6 mm (−0.23%) | 99.8 km/h | 110.3 mm | Very close | Compare |
| 245/50R18 | 702.2 mm | −2.5 mm (−0.35%) | 99.6 km/h | 122.5 mm | Very close | Compare |
| 225/60R17 | 701.8 mm | −2.9 mm (−0.41%) | 99.6 km/h | 135.0 mm | Very close | Compare |
| 215/65R17 | 711.3 mm | +6.6 mm (+0.94%) | 100.9 km/h | 139.8 mm | Close | Compare |
| 255/45R19 | 712.1 mm | +7.4 mm (+1.05%) | 101.1 km/h | 114.8 mm | Close | Compare |
| 235/60R17 | 713.8 mm | +9.1 mm (+1.29%) | 101.3 km/h | 141.0 mm | Close | Compare |
| 235/45R19 | 694.1 mm | −10.6 mm (−1.50%) | 98.5 km/h | 105.8 mm | Close | Compare |
- Keeping your wheels, the closest is 245/50R18 at 702.2 mm, −2.5 mm (−0.35%) from the original. With the speedometer on 100 km/h, the car would actually be doing about 99.6 km/h. Ground clearance drops by about 1.3 mm.
- Moving up to 19-inch wheels, the closest height match is 245/45R19 (−0.23%), with the sidewall dropping from 123.8 mm to 110.3 mm.
- Going down to 17-inch wheels, 225/60R17 (−0.41%) is the closest match and raises the sidewall to 135.0 mm.
- A larger or wider tire also changes acceleration, fuel use and steering weight, so look beyond the percentage.
Buying 225/55R18 tires
Passenger tires in this size come in eco, comfort and sport lines. Japanese and European brands usually cost more than Asian ones, and the difference shows in noise, wet braking and tread life.
Check the production date in the DOT code before paying.
Check current prices
Search by brand
Links open marketplace search results; prices change constantly and not every brand makes this size.
Load index and speed rating for 225/55R18
The code after the size on the sidewall, as in 225/55R18 98H, is the load index and speed symbol. The common ratings for this size:
| Version | Index | Per tire | Four tires |
|---|---|---|---|
| Standard load (SL) | 98 | 750 kg | 3,000 kg |
| Extra load (XL) | 102 | 850 kg | 3,400 kg |
The new tire's load index and speed symbol must be no lower than the door placard, and it only carries its rated load at the correct pressure.
Common speed symbols in this size
H
210 km/h
V
240 km/h
225/55R18 questions
How tall is a 225/55R18 tire?
About 27.7 inches, or 704.7 mm, from top to bottom before it carries weight. Each sidewall is 123.8 mm tall and the tire is 225 mm (8.9 in) wide.
Which cars use 225/55R18 tires?
No car in our data is fitted with 225/55R18 from the factory, but its height is close to the original size on Toyota Yaris Cross HEV, Mazda CX-30, BYD ATTO 3, MG HS / HS PHEV and BYD Seal, so it works as a replacement size.
Can I fit 245/50R18 instead of 225/55R18?
Size-wise, yes: the height differs by −0.35% (−2.5 mm), so an indicated 100 km/h is really about 99.6 km/h. The tread is 20 mm wider. Check rim width and load index first.
How much weight can a 225/55R18 tire carry?
Most standard-load versions carry load index 98: 750 kg per tire, 3,000 kg across four. XL versions are rated 102, or 850 kg per tire. Look for the number after the size on the sidewall, as in 225/55R18 98H.
Other 18-inch sizes
To compare other sizes yourself, use the tire size calculator; changing rim size, try plus/minus sizing; and see speedometer error by speed.