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.

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.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top