Tire Size 235/40r18 vs 245/40r18

The endless options and technical jargon can be confusing for the average driver. That’s why we’re here to help simplify the process by comparing two popular tire sizes, the 235/40r18 and 245/40r18. In short, 235/40R18 is equivalent to 25.4×9.3R18 and 245/40R18 is equivalent to 25.7×9.6R18.

235/40r18 vs 245/40r18 Table

Specification 235/40r18 245/40r18 Difference
Diameter 25.4″ 25.72″ 0.31 inches
Width 9.25″ 9.65″ 0.39 inches
Circumference 79.8″ 80.79″ 0.99 inches
Sidewall Height 3.7″ 3.86″ 0.16 inches
Revolutions 793.97 784.25 9.72

Alternative Tire Size for 245/40r18
It’s important to ensure that the overall diameter of the new tire is within 3% of the original tire. The 245/40r18 tire size has 60 compatible tire size options for replacement.

Tire Size Overall Diameter Difference
295/30R18 25″ (635 mm) -2.8%
255/35R18 25″ (635 mm) -2.8%
225/40R18 25.1″ (637 mm) -2.5%
305/30R18 25.2″ (641 mm) -1.8%
205/45R18 25.2″ (641 mm) -1.8%
265/35R18 25.3″ (643 mm) -1.5%
155/60R18 25.3″ (643 mm) -1.5%
145/65R18 25.4″ (645 mm) -1.2%
235/40R18 25.4″ (645 mm) -1.2%
315/30R18 25.5″ (647 mm) -0.9%
135/70R18 25.5″ (647 mm) -0.9%
275/35R18 25.6″ (649 mm) -0.6%
215/45R18 25.6″ (651 mm) -0.3%
285/35R18 25.9″ (657 mm) 0.6%
225/45R18 25.9″ (659 mm) 0.9%
335/30R18 25.9″ (659 mm) 0.9%
145/70R18 26″ (661 mm) 1.2%
255/40R18 26″ (661 mm) 1.2%
185/55R18 26″ (661 mm) 1.2%
205/50R18 26.1″ (663 mm) 1.5%
295/35R18 26.1″ (663 mm) 1.5%
345/30R18 26.2″ (665 mm) 1.8%
235/45R18 26.3″ (669 mm) 2.5%
265/40R18 26.3″ (669 mm) 2.5%
305/35R18 26.4″ (671 mm) 2.8%

Alternative Tire Size for 235/40r18
it’s crucial to make sure that the overall diameter of the new tire is no more than 3% different from the original tire. The 235/40r18 tire size offers 60 compatible tire sizes for replacement.

Tire Size Overall Diameter Difference
245/35R18 24.8″ (629 mm) -2.5%
285/30R18 24.8″ (629 mm) -2.5%
215/40R18 24.8″ (629 mm) -2.5%
125/70R18 24.9″ (633 mm) -1.9%
255/35R18 25″ (635 mm) -1.6%
225/40R18 25.1″ (637 mm) -1.2%
305/30R18 25.2″ (641 mm) -0.6%
205/45R18 25.2″ (641 mm) -0.6%
265/35R18 25.3″ (643 mm) -0.3%
155/60R18 25.3″ (643 mm) -0.3%
145/65R18 25.4″ (645 mm) 0%
315/30R18 25.5″ (647 mm) 0.3%
135/70R18 25.5″ (647 mm) 0.3%
275/35R18 25.6″ (649 mm) 0.6%
215/45R18 25.6″ (651 mm) 0.9%
245/40R18 25.7″ (653 mm) 1.2%
285/35R18 25.9″ (657 mm) 1.9%
225/45R18 25.9″ (659 mm) 2.2%
335/30R18 25.9″ (659 mm) 2.2%
185/55R18 26″ (661 mm) 2.5%
145/70R18 26″ (661 mm) 2.5%
295/35R18 26.1″ (663 mm) 2.8%
205/50R18 26.1″ (663 mm) 2.8%

Overall Diameter
The 235 40r18 size has an overall diameter of 25.4 inches, while the 245 40r18 size has an overall diameter of 25.72 inches. This means that the 245 40r18 sizes will be slightly larger in diameter than the 235 40r18 sizes. The difference in those tire sizes is 0.31 inches or about 1.2%.

The overall diameter is important to consider because it can affect your vehicle’s performance. Larger tires can provide better grip and handling, making your car less fuel efficient.

Section Width
The 235 40r18 size has a section width of 9.25 inches, while the 245 40r18 size has a section width of 9.65 inches. This means the 245 40r18 sizes will be about 4.3% wider than the 235 40r18 sizes.

The section width is important to consider because it can affect your vehicle’s performance. Wider tires can provide better grip and handling, but they can also make your car less fuel efficient.

Circumference
The 235 40r18 size has a circumference of 79.8 inches, while the 245 40r18 size has a circumference of 80.79 inches. This means that the 245 40r18 sizes will be about 0.99 inches or about 1.2%.

The difference in circumference is important to consider because it can affect the speedometer readings on your vehicle. If you’re planning to use the tires for racing, you’ll want to ensure that the speedometer is accurate.

Revolutions Per Mile
The 235 40r18 size has revolutions per mile of 793, while the 245 40r18 size has revolutions per mile of 784. This means that the 245 40r18 sizes will be about 1.2% smaller in circumference than the 235 40r18 sizes.

Sidewall Height
The 235 40r18 size has a sidewall height of 3.7 inches, while the 245 40r18 size has a sidewall height of 3.86 inches. This means that the 245 40r18 sizes will be about 0.16 inches or about 4.3% taller in sidewall height than the 235 40r18 sizes.

The sidewall height is essential to consider because it can affect your vehicle’s performance. Taller tires can provide better grip and handling, making your car less fuel efficient.

Wheel Size
The 235 40r18 size has a wheel size of 18 inches, while the 245 40r18 size also has a wheel size of 18 inches. This means there is no wheel size difference between the two sizes. The 235 40r18 and 245 40r18 sizes will both fit on 18-inch rims.

Construction Type
The 235 40r18 size is available in radial construction, while the 245 40r18 size is also available in radial construction. Radial tires are the most common type of tire construction, and they’re characterized by the steel belts that run radially around the tire. Radial tires are known for their durability, stability, and fuel efficiency.

Our Observation
Based on the comparison table, the 245/40r18 tire size is slightly larger in overall diameter, section width, circumference, and sidewall height compared to the 235/40r18 tire size. This means that the 245/40r18 tire size may offer better handling and a more comfortable ride.

However, the 235/40r18 tire size has a slightly higher RPM, which may result in better fuel efficiency. Ultimately, the choice between these two tire sizes depends on your personal preference and the specific needs of your vehicle.

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