245/40R18 tire size
A 245/40R18 tire is 245 mm wide with a 98.0 mm sidewall, 40% of the width, on a 18-inch rim, which puts the whole tire at 653.2 mm, or about 25.7 inches, tall. No model in our data leaves the factory on it, but it can replace the original size on 17 models within 3% of the height.
Overall height
653.2 mm
25.7 in
Sidewall
98.0 mm
40%
Circumference
2,052 mm
Revs per km
487
Actual dimensions of 245/40R18
| Section width | 245 mm (9.6 in) |
| Sidewall height | 98.0 mm (3.86 in) |
| Rim diameter | 18 in (457.2 mm) |
| Overall diameter | 653.2 mm (25.7 in) |
| Circumference | 2,052 mm |
| Revolutions per km | 487 |
| Inch notation (height x width) | 25.7x9.6R18 |
Worked out: sidewall 245 x 0.4 = 98 mm, rim 18 x 25.4 = 457.2 mm, overall 457.2 + (98 x 2) = 653.2 mm, circumference 3.1416 x 653.2 = 2,052 mm. One turn of the tire moves the car about 2.05 m, which is 487 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 245/40R18 from the factory
No model sold in Thailand in our data leaves the factory on 245/40R18.
Cars that can switch to 245/40R18
These cars leave the factory on another size within 3% of the height of 245/40R18. Whether it fits still depends on rim width and wheel-well clearance.
| Model | Factory size | Height difference | Wheel |
|---|---|---|---|
| Mazda32019–present | 215/45R18 | +0.38% | Same wheel |
| Honda Civic (FE)2021–present | 235/40R18 | +1.24% | Same wheel |
| Toyota Camry HEV2024–present | 235/45R18 | −2.32% | Same wheel |
| Honda Accord e:HEV2024–present | 235/45R18 | −2.32% | Same wheel |
| MG4 Electric2022–present | 235/45R18 | −2.32% | Same wheel |
| Tesla Model 32024–present | 235/45R18 | −2.32% | Same wheel |
| Mazda CX-32015–present | 215/50R18 | −2.83% | Same wheel |
| ORA Good Cat2021–present | 215/50R18 | −2.83% | Same wheel |
| Honda Civic (FC)2016–2021 | 215/50R17 | +0.99% | Needs 18-inch wheels |
| MG5Current model | 215/50R17 | +0.99% | Needs 18-inch wheels |
| MG ZSCurrent model | 215/55R16 | +1.60% | Needs 18-inch wheels |
| Honda BR-V2022–present | 215/60R16 | −1.69% | Needs 18-inch wheels |
Showing the 12 closest of 17 models.
Sizes that can replace 245/40R18
Sizes within ±3% of the overall height of 245/40R18. “At 100 km/h” is the real speed when the speedometer reads 100.
| Size | Height | Difference | At 100 km/h | Sidewall | Match | Compare |
|---|---|---|---|---|---|---|
| 245/35R19 | 654.1 mm | +0.9 mm (+0.14%) | 100.1 km/h | 85.8 mm | Very close | Compare |
| 245/45R17 | 652.3 mm | −0.9 mm (−0.14%) | 99.9 km/h | 110.3 mm | Very close | Compare |
| 215/45R18 | 650.7 mm | −2.5 mm (−0.38%) | 99.6 km/h | 96.8 mm | Very close | Compare |
| 225/50R17 | 656.8 mm | +3.6 mm (+0.55%) | 100.6 km/h | 112.5 mm | Close | Compare |
| 235/35R19 | 647.1 mm | −6.1 mm (−0.93%) | 99.1 km/h | 82.3 mm | Close | Compare |
| 215/50R17 | 646.8 mm | −6.4 mm (−0.98%) | 99.0 km/h | 107.5 mm | Close | Compare |
| 225/45R18 | 659.7 mm | +6.5 mm (+1.00%) | 101.0 km/h | 101.3 mm | Close | Compare |
| 255/35R19 | 661.1 mm | +7.9 mm (+1.21%) | 101.2 km/h | 89.3 mm | Close | Compare |
- Keeping your wheels, the closest is 215/45R18 at 650.7 mm, −2.5 mm (−0.38%) 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 245/35R19 (+0.14%), with the sidewall dropping from 98.0 mm to 85.8 mm.
- Going down to 17-inch wheels, 245/45R17 (−0.14%) is the closest match and raises the sidewall to 110.3 mm.
- A larger or wider tire also changes acceleration, fuel use and steering weight, so look beyond the percentage.
Buying 245/40R18 tires
Low-profile sizes are mostly performance tires and price rises with W or Y speed ratings; comfort-focused models exist in the same size if you do not drive hard.
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 245/40R18
The code after the size on the sidewall, as in 245/40R18 93V, is the load index and speed symbol. The common ratings for this size:
| Version | Index | Per tire | Four tires |
|---|---|---|---|
| Standard load (SL) | 93 | 650 kg | 2,600 kg |
| Extra load (XL) | 97 | 730 kg | 2,920 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
V
240 km/h
W
270 km/h
Y
300 km/h
245/40R18 questions
How tall is a 245/40R18 tire?
About 25.7 inches, or 653.2 mm, from top to bottom before it carries weight. Each sidewall is 98.0 mm tall and the tire is 245 mm (9.6 in) wide.
Which cars use 245/40R18 tires?
No car in our data is fitted with 245/40R18 from the factory, but its height is close to the original size on Mazda3, Honda Civic (FE), Toyota Camry HEV, Honda Accord e:HEV and MG4 Electric, so it works as a replacement size.
Can I fit 215/45R18 instead of 245/40R18?
Size-wise, yes: the height differs by −0.38% (−2.5 mm), so an indicated 100 km/h is really about 99.6 km/h. The tread is 30 mm narrower. Check rim width and load index first.
How much weight can a 245/40R18 tire carry?
Most standard-load versions carry load index 93: 650 kg per tire, 2,600 kg across four. XL versions are rated 97, or 730 kg per tire. Look for the number after the size on the sidewall, as in 245/40R18 93V.
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.