Tire Size 225/45r18 vs 245/40r18
The width is the primary difference between the 225/45r18 and 245/40r18 tire sizes. The 245/40r18 has a wider width of 9.65 inches (245mm), which is about 8.2% more than the 225/45r18 tire width of 8.86 inches (225mm). This increased width can lead to better traction and stability but also affect fuel efficiency and ride comfort.
225/45r18 vs 245/40r18 Table
| Feature | 245/40r18 | 225/45r18 | Difference |
|---|---|---|---|
| Overall Diameter | 25.72″ | 25.97″ | 0.26″ |
| Width inches | 9.65″ | 8.86″ | 0.79″ |
| Circumference | 80.79″ | 81.59″ | 0.8″ |
| Sidewall Height | 3.86″ | 3.99″ | 0.13″ |
| Revolution | 784.25 | 776.52 | 7.73 |
| Rim Size | 18″ | 18″ | Same |
| Rim Width Range | 8.0-9.5″ | 7.0-8.5″ | Different |
Overall Diameter
The 225/45r18 tire has a diameter of 25.97 inches, slightly larger by 1% (0.26 inches) compared to the 245/40r18 tire. A larger diameter generally offers more ground clearance, which is advantageous in off-road driving or rough terrain. It also results in a lower speedometer reading.
Conversely, a smaller diameter tire reduces ground clearance, potentially leading to vehicle damage on rough roads, but will result in a higher speedometer reading. The 1% difference falls within the recommended 3% difference from the factory recommended tires, making both options viable.
Section Width
The 245/40r18 tire is approximately 8.2% wider than the 225/45r18 tire. A wider tire generally provides improved traction due to a larger contact patch, enhancing grip during acceleration, braking, and cornering.
However, wider tires often generate more road noise due to increased contact area. Conversely, a narrower tire like the 225/45r18 has less surface area in contact with the road, potentially reducing grip in wet or slippery conditions.
Circumference
The circumference of the 225/45r18 tire is marginally larger by 1% compared to the 245/40r18 tire. An increased circumference will result in lower speedometer readings, whereas a decreased circumference will result in higher speedometer readings.
Revolutions Per Mile
The 225/45r18 tire completes fewer revolutions per mile, potentially leading to an extended lifespan due to reduced wear and tear. Conversely, the 245/40r18 tire completes more revolutions per mile, which might increase wear and shorten its lifespan. However, the difference is only 1%, which might not significantly impact the tire’s lifespan.
Sidewall Height
The 225/45r18 tire has a 3.3% taller sidewall than the 245/40r18 tire. A taller sidewall absorbs more bumps and road irregularities, providing a smoother ride and increased traction on snowy or icy roads. Conversely, a shorter sidewall on the 245/40r18 tire may lead to a harsher ride but offers a sportier and more aggressive look.
Rim Size
Both tires can be mounted on 18″ rims, although the recommended rim widths differ. The 245/40r18 tire can accommodate rims of widths 8.0-9.5″, making them more suitable for a sportier, aggressive look.
On the other hand, the 225/45r18 tire accommodates a narrower rim range (7.0-8.5″), giving them a more classic or conservative appearance.
How much taller is a 245/40r18 tire than a 225/45r18?
The height of a 245/40r18 tire is 25.72 inches (653.2 mm), whereas the height of a 225/45r18 tire is 25.97 inches (659.7 mm). This makes the 225/45r18 tire approximately 0.26 inches (or 6.5 mm) taller than the 245/40r18 tire.
How much wider is a 245/40r18 tire than a 225/45r18?
Regarding width, the 245/40r18 tire measures 9.65 inches (245 mm) wide, and the 225/45r18 tire measures 8.86 inches (225 mm) wide. Consequently, the 245/40r18 tire is about 0.79 inches (or 20 mm) wider than the 225/45r18 tire.
Can I use 245/40r18 instead of 225/45r18?
The overall diameter of a 245/40r18 tire is 25.72 inches, whereas the 225/45r18 tire has a diameter of 25.97 inches. The difference between these two sizes is roughly 0.26 inches or about 1%. Given this is less than the suggested 3% variance, it may be possible to use a 245/40r18 tire instead of a 225/45r18.
Can I put a 245/40r18 on a 225/45r18?
The 245/40r18 tire has a rim width range of 8.0-9.5″, while the 225/45r18 tire has a range of 7.0-8.5″. The two ranges overlap at 8.0-8.5″, which suggests that it might be possible to mount a 245/40r18 tire on a rim intended for a 225/45r18 tire.
Our Observation
The choice between the 225/45r18 and 245/40r18 largely depends on your driving conditions and personal preferences. The 225/45r18 tire, with its larger diameter, higher sidewall, and smaller width, offers a smoother ride and potentially a longer lifespan, ideal for everyday, comfortable driving.
Conversely, the 245/40r18 tire, with its wider tread and smaller sidewall, provides better traction and a sportier look, making it suitable for performance-oriented drivers.
Remember, while both options fall within the recommended diameter difference, always consult a tire professional or your vehicle’s manufacturer before changing your tire size to ensure safety and performance.
