235/55R18 tire size
A 235/55R18 tire is 235 mm wide with a 129.3 mm sidewall, 55% of the width, on a 18-inch rim, which puts the whole tire at 715.7 mm, or about 28.2 inches, tall. No model in our data leaves the factory on it, but it can replace the original size on 2 models within 3% of the height.
Overall height
715.7 mm
28.2 in
Sidewall
129.3 mm
55%
Circumference
2,248 mm
Revs per km
445
Actual dimensions of 235/55R18
| Section width | 235 mm (9.3 in) |
| Sidewall height | 129.3 mm (5.09 in) |
| Rim diameter | 18 in (457.2 mm) |
| Overall diameter | 715.7 mm (28.2 in) |
| Circumference | 2,248 mm |
| Revolutions per km | 445 |
| Inch notation (height x width) | 28.2x9.3R18 |
Worked out: sidewall 235 x 0.55 = 129.25 mm, rim 18 x 25.4 = 457.2 mm, overall 457.2 + (129.25 x 2) = 715.7 mm, circumference 3.1416 x 715.7 = 2,248 mm. One turn of the tire moves the car about 2.25 m, which is 445 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 235/55R18 from the factory
No model sold in Thailand in our data leaves the factory on 235/55R18.
Cars that can switch to 235/55R18
These cars leave the factory on another size within 3% of the height of 235/55R18. Whether it fits still depends on rim width and wheel-well clearance.
Sizes that can replace 235/55R18
Sizes within ±3% of the overall height of 235/55R18. “At 100 km/h” is the real speed when the speedometer reads 100.
| Size | Height | Difference | At 100 km/h | Sidewall | Match | Compare |
|---|---|---|---|---|---|---|
| 235/50R19 | 717.6 mm | +1.9 mm (+0.27%) | 100.3 km/h | 117.5 mm | Very close | Compare |
| 235/60R17 | 713.8 mm | −1.9 mm (−0.27%) | 99.7 km/h | 141.0 mm | Very close | Compare |
| 255/45R19 | 712.1 mm | −3.6 mm (−0.50%) | 99.5 km/h | 114.8 mm | Close | Compare |
| 215/65R17 | 711.3 mm | −4.4 mm (−0.61%) | 99.4 km/h | 139.8 mm | Close | Compare |
| 225/65R17 | 724.3 mm | +8.6 mm (+1.20%) | 101.2 km/h | 146.3 mm | Close | Compare |
| 225/55R18 | 704.7 mm | −11.0 mm (−1.54%) | 98.5 km/h | 123.8 mm | Close | Compare |
| 225/60R18 | 727.2 mm | +11.5 mm (+1.61%) | 101.6 km/h | 135.0 mm | Close | Compare |
| 245/40R20 | 704.0 mm | −11.7 mm (−1.63%) | 98.4 km/h | 98.0 mm | Close | Compare |
- Keeping your wheels, the closest is 225/55R18 at 704.7 mm, −11.0 mm (−1.54%) from the original. With the speedometer on 100 km/h, the car would actually be doing about 98.5 km/h. Ground clearance drops by about 5.5 mm.
- Moving up to 19-inch wheels, the closest height match is 235/50R19 (+0.27%), with the sidewall dropping from 129.3 mm to 117.5 mm.
- Going down to 17-inch wheels, 235/60R17 (−0.27%) is the closest match and raises the sidewall to 141.0 mm.
- A larger or wider tire also changes acceleration, fuel use and steering weight, so look beyond the percentage.
Buying 235/55R18 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 235/55R18
The code after the size on the sidewall, as in 235/55R18 100H, is the load index and speed symbol. The common ratings for this size:
| Version | Index | Per tire | Four tires |
|---|---|---|---|
| Standard load (SL) | 100 | 800 kg | 3,200 kg |
| Extra load (XL) | 104 | 900 kg | 3,600 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
235/55R18 questions
How tall is a 235/55R18 tire?
About 28.2 inches, or 715.7 mm, from top to bottom before it carries weight. Each sidewall is 129.3 mm tall and the tire is 235 mm (9.3 in) wide.
Which cars use 235/55R18 tires?
No car in our data is fitted with 235/55R18 from the factory, but its height is close to the original size on Mazda CX-5 and Honda CR-V, so it works as a replacement size.
Can I fit 225/55R18 instead of 235/55R18?
Size-wise, yes: the height differs by −1.54% (−11.0 mm), so an indicated 100 km/h is really about 98.5 km/h. The tread is 10 mm narrower. Check rim width and load index first.
How much weight can a 235/55R18 tire carry?
Most standard-load versions carry load index 100: 800 kg per tire, 3,200 kg across four. XL versions are rated 104, or 900 kg per tire. Look for the number after the size on the sidewall, as in 235/55R18 100H.
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.