Tire Size 235/40r18 in inches
The tire size 235/40r18 is a popular choice among car enthusiasts due to its balance of performance and aesthetics. We will delve into the various dimensions and specifications of this tire size, providing both metric and inch measurements for a comprehensive understanding.
235/40r18 in inches
The table provided below offers extensive details to facilitate a better understanding of the tire features and metrics breakdown
| Feature | Metric | Inches |
|---|---|---|
| Tire Height | 645 mm | 25.4″ |
| Tread Width | 235 mm | 9.3″ |
| Rim Diameter | 457.2 mm | 18″ |
| Sidewall Height | 94 mm | 3.7″ |
| Circumference | 2025.3 mm | 79.8″ |
| Revolutions | 494 per km | 794 per mile |
What does 235/40r18 mean?
The tire size 235/40R18 is a standardized format used to describe the dimensions and specifications of a tire. Let’s break down what each number and letter in the size designation represents:
- 235: The first number, 235, indicates the tire’s section width in millimeters. It represents the tire’s widest point, from sidewall to sidewall, when mounted on a specified rim width. In this case, the tire has a section width of 235 mm.
- 40: The second number, 40, is the aspect ratio. It is a percentage that represents the ratio of the tire’s sidewall height to its section width. In this case, the sidewall height is 40% of the tire’s section width.
- R: The letter “R” stands for radial construction. Most modern tires feature radial construction, where the internal plies of the tire run radially across the tire from bead to bead. Radial tires offer numerous benefits, such as improved fuel efficiency, better traction, and a smoother ride.
- 18: The final number, 18, indicates the rim diameter in inches. It specifies the wheel size onto which the tire is intended to be mounted. In this case, the tire is designed to fit an 18-inch diameter rim.
Overall, the tire size 235/40R18 specifies a tire with a section width of 235 mm, an aspect ratio of 40%, radial construction, and intended for an 18-inch diameter rim. Selecting tires compatible with the vehicle’s recommended tire size is important to ensure proper fitment and optimal performance.
Replacement Tire Size
It is crucial to ensure that they fall within a 3% range of the overall diameter of the original 275/65r20 tire
| 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% |
| 205/45R18 | 25.2″ (641 mm) | -0.6% |
| 265/35R18 | 25.3″ (643 mm) | -0.3% |
| 155/60R18 | 25.3″ (643 mm) | -0.3% |
| 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% |
| 185/55R18 | 26″ (661 mm) | 2.5% |
| 145/70R18 | 26″ (661 mm) | 2.5% |
| 255/40R18 | 26″ (661 mm) | 2.5% |
| 295/35R18 | 26.1″ (663 mm) | 2.8% |
| 205/50R18 | 26.1″ (663 mm) | 2.8% |
Tire Height
The overall diameter of a tire refers to the distance between the outer edges of the tire when mounted on a rim. For the 235/40r18 tire, the overall diameter measures 645 mm or approximately 25.4 inches. This measurement is crucial as it determines the fitment and compatibility of the tire with the vehicle.
Tread Width
The tread width represents the width of the tire’s contact patch with the road surface. In the case of the 235/40r18 tire, the tread width measures 235 mm or approximately 9.3 inches. A wider tread width often provides improved traction and handling characteristics, making it a favorable choice for sports-oriented vehicles.
Rim Diameter
The rim diameter refers to the size of the wheel onto which the tire is mounted. For the 235/40r18 tire, the rim diameter measures 457.2 mm or 18 inches. Ensuring that the tire and rim diameters are compatible is essential to guarantee a secure and proper fitment.
Sidewall Height
The sidewall height indicates the distance between the rim and the outer edge of the tire. In the case of the 235/40r18 tire, the sidewall height is 94 mm or approximately 3.7 inches. Sidewall height plays a role in ride comfort, with taller sidewalls providing more cushioning and a smoother driving experience.
Circumference
The circumference of a tire refers to the distance around its outer edge. For the 235/40r18 tire, the circumference measures 2025.3 mm or approximately 79.8 inches. The circumference is closely linked to the revolutions per mile, which we will explore in the next section.
Revolutions Per Mile
Revolutions per mile represent the number of complete rotations a tire makes over the distance of one mile. The 235/40r18 tire rotates approximately 794 times per mile or 494 times per kilometer. This specification provides insights into the tire’s rolling characteristics and can impact speedometer accuracy.
Tire Construction
While not specifically mentioned in the provided data, it is worth noting that the “R” in the tire size 235/40r18 stands for “Radial.” Radial tires are the most common type in use today due to their numerous advantages, including better fuel efficiency, improved traction, and enhanced tread life. Radial construction involves layers of fabric cords positioned radially, allowing for better flexibility and a more comfortable ride.
Our Observation
Upon analyzing the dimensions and specifications of the 235/40r18 tire size, several key points come to light. The tire’s overall diameter of 645 mm (25.4 inches) and tread width of 235 mm (9.3 inches) indicate a balanced combination of performance and stability. The 18-inch rim diameter is popular among sporty and high-performance vehicles, further emphasizing the tire’s capabilities.
With a sidewall height of 94 mm (3.7 inches), the tire strikes a balance between ride comfort and responsive handling. The circumference of 2025.3 mm (79.8 inches) provides insights into the tire’s rolling characteristics and can impact speedometer accuracy, an important consideration for drivers who rely on accurate speed readings.
The 235/40r18 tire’s revolutions per mile value of approximately 794 indicates how frequently the tire rotates over a given distance. This information is useful for various calculations, such as determining fuel consumption and estimating tire wear.
