235/40R18 Tires

Understanding 235/40R18 tire size is crucial for making informed decisions when purchasing new tires, whether it is for replacement or upgrade, as it plays an important role in your vehicle's performance and safety. Let's explore 235/40R18 tire specs and dimensions, what vehicles come equipped with 235/40R18 tires, what are its replacement options, and where to buy 235/40R18 tires at lowest prices online.

Buy 235/40R18 Tires from $78.96

How to read 235/40R18 tire size?

235/40R18 is a Metric tire size that is commonly used on passenger and crossover vehicles. It also comes in a P-Metric (P235/40R18) variant.

Let us decode each aspect of 235/40R18 tire size dimensions for better understanding:

  • 235 indicates tire's section width, which includes the entire width of the tire from one sidewall to the other. The tread width is typically a bit narrower than the section width. Section width of 235/40R18 tire is 235 millimeters.
  • 40 represents the aspect ratio of a tire. It is the ratio of the tire's sidewall height to its width. For 235/40R18 tire, the sidewall height is 40% of its tread width.
  • R denotes that tire has radial construction.
  • 18 indicates the wheel diameter in inches that the tire is designed to fit. 235/40R18 can be mounted on rims with 18 inches in diameter.

You can learn more about tire size markings on tire sidewall with our comprehensive guide on how to read tire size.

235/40R18 Tire Dimensions

Compare and visualize 235/40R18 tire dimensions in both inches and millimeters. Tire size calculator will help you calculate the dimensions of any tire size.

235/40R18 Section Width
9.3"
25.4"
235/40R18 Tire Side
Tire Circumference
79.8"
18"
3.7"
794 Revs/Mile
Metric Inches
Tire Width 235 mm 9.3"
Aspect Ratio 40%
Rim Diameter 457 mm 18"
Tire Diameter 645 mm 25.4"
Sidewall Height 94 mm 3.7"
Circumference 2025 mm 79.8"
Revolutions 494 per km 794 per mile

235/40R18 Tire Width

How wide is 235/40R18 tire? Tire width is the measurement of the tire's cross-section at its widest point. 235/40R18 tire is 235 millimeters or 9.3 inches wide.

Tires that are 235 millimeters wide come equipped on a variety of crossovers, minivans, passenger cars, pickup trucks, sport utility vehicles and vans.

Tires with width of 235 millimeters are considered fairly wide. This width offers enhanced traction and stability, which is crucial for handling heavier vehicles or providing better performance and driving dynamics.

Tire width plays a pivotal role in determining a vehicle's handling, safety, and efficiency. It is crucial to consider the compatibility of tire width with the vehicle's design and the manufacturer's specifications to maintain optimal functionality and ensure safety.

Tire Width
9.3"

235/40R18 Aspect Ratio

Tire aspect ratio represents the height of the tire's sidewall as a percentage of its width. 235/40R18 tire size has an aspect ratio of 40%.

Tires with an aspect ratio of 40 fall into the category of low profile tires. These are commonly found on sports cars and high-performance luxury vehicles. The low profile (short sidewall height relative to tire width) enhances the vehicle's handling and responsiveness, particularly at high speeds and during sharp cornering. They contribute to a car's aggressive and sporty aesthetic.

Wider contact patch with the road surface allows for better traction, which is crucial for acceleration, braking, and cornering performance. However, it may also lead to increased road noise and a decrease in fuel or energy efficiency compared to tires with higher aspect ratios.

235/40R18 Rim Diameter

Rim diameter refers to the diameter of the wheel on which the tire is mounted, commonly measured in inches. 235/40R18 rim size is 18 inches, meaning that tire can be mounted on 18-inch wheels. Rim diameter directly correlates with the overall diameter of the tire and affects various aspects of vehicle performance and aesthetics.

Tires with rim diameter of 18 inches are equipped on a select crossover, minivan, passenger car, pickup truck and sport utility vehicle models.

18-inch rims are typical for performance-oriented vehicles, including sports cars and high-end sedans. 18-inch rims allow for the fitting of larger brakes, which are crucial for high-performance vehicles, and can also enhance the vehicle's handling characteristics and appearance.

When selecting a rim diameter, it's crucial to consider the vehicle's design specifications, as altering the rim size can affect the speedometer and odometer calibration, vehicle handling, suspension geometry, and brake clearance.

Rim Diameter
18"

235/40R18 Tire Diameter

How tall is 235/40R18 tire? Tire diameter represens the total height of a tire, including the rim, when it is fully inflated and not under load. 235/40R18 diameter is 645 millimeters or 25.4 inches.

Tire height affects the clearance between the tire and the vehicle's body or chassis, influences the vehicle's ground clearance, and can impact the accuracy of the vehicle's speedometer and odometer.

For standard passenger cars, tire diameters typically range from about 24 to 30 inches. This includes sedans, hatchbacks, small SUVs, and minivans. Light trucks and larger SUVs might have tires on the higher end of this range or slightly above, often between 29 to 33 inches. Sports cars and high-performance vehicles may have similar diameter ranges as standard passenger cars, but they often feature wider tires with a lower aspect ratio, which can slightly affect the overall diameter. The range for these vehicles is typically between 24 to 30 inches, focusing more on width and profile for performance. Off-road vehicles, including larger SUVs, trucks, and specialized vehicles, often have larger tire diameters to handle rough terrain better. The diameters for these vehicles can range from about 31 to 40 inches or more, depending on the level of off-road capability and customization.

Tire Diameter
25.4"

235/40R18 Sidewall Height

Tire sidewall height, determined by the aspect ratio of a tire, represents the height of the tire's sidewall, measured from the edge of the rim to the top of the tread. 235/40R18 tire sidewall is 94 millimeters or 3.7 inches tall.

Sidewall height affects the tire's ability to dissipate heat and impacts its load-bearing capacity. It also plays a role in aesthetic appeal for many drivers, influencing the overall look of the vehicle.

Tires with a sidewall height of 3.7" are considered low profile. Lower sidewall height, commonly seen in performance tires, generally enhances handling and steering response by reducing flex and deformation under stress. This results in a firmer ride quality and increased stability at higher speeds, making them suitable for sports and performance vehicles.

Sidewall Height
3.7"

235/40R18 Circumference

Tire circumference is the total distance around the outer edge of the tire. 235/40R18 tire has a circumference of 2025 millimeters or 79.8 inches.

Tires with a circumference of 79.8 inches are typically found on small cars and compact vehicles. The advantage of smaller circumference tires is that they generally provide better fuel efficiency, enhanced acceleration and more responsive handling for easier maneuverability. However, they may offer less traction and a rougher ride compared to larger tires.

Tire circumference directly influences the speedometer and odometer readings of a vehicle. Mismatched tire circumferences, especially on the same axle, can lead to uneven wear, handling issues, and even mechanical damage, particularly in all-wheel or four-wheel-drive vehicles.

235/40R18 Circumference
Tire Circumference
79.8"

235/40R18 Revolutions

Tire revolutions metric reflects the number of times a tire rotates over a fixed distance. This figure is inherently tied to the tire's circumference - the larger the circumference, the fewer the revolutions needed to cover a mile, and vice versa. 235/40R18 tire makes 494 revolutions per kilometer or 794 revolutions per mile.

Number of the revolutions a tire makes affects greatly vehicle's performance, from speed and distance measurement accuracy to handling, fuel efficiency, and wear and tear.

Popular 235/40R18 tire models

Listed below are most affordable tire models available in 235/40R18 tire size.

Shop more 235/40R18 tires with tire finder.

What is 235/40R18 in inches?

When converted to inches, 235/40R18 tire size is equivalent to 25.4x9.3R18. 25.4 inches indicate the tire diameter, 9.3 inches represent tread width, and 18 inches is the diameter of a rim the tire can be mounted on.

Conversion of 235/40R18 to inches involves a series of steps that translate the metric measurements of tire width, aspect ratio, and rim diameter into their inch equivalents. This conversion is crucial for understanding tire sizes in a format that may be more intuitive or necessary for specific applications, allowing for better informed decisions regarding tire selection and compatibility.

First, the width of the tire (235 mm) is converted to inches by dividing by 25.4 (since there are 25.4 millimeters in an inch). Secondly, to determine the sidewall height in inches, calculate the height of the tire's sidewall as a percentage of its width (the aspect ratio), then convert this measurement from millimeters to inches. In the case of a 235/40R18 tire, the sidewall height is 40% of 235 mm, which converts to approximately 3.7 inches. Lastly, to ascertain the overall diameter of the tire, sum twice the sidewall height with the diameter of the rim (already in inches). Therefore, for a 235/40R18 tire, the overall diameter is the sum of twice the sidewall height (3.7 x 2) plus the rim diameter (18 inches), culminating in an overall diameter of about 25.4 inches.

235/40R18 Vehicle Fitment

There are 39 vehicle models that use 235/40R18 as an original equipment tire size. It's important to consult your vehicle's owner manual or a tire fitment guide specific to your car model to ensure this tire size is compatible with your vehicle. Vehicle manufacturers recommend specific tire sizes to ensure optimal performance and safety.

Select your vehicle model for its OEM tire size configuration.

What are replacement sizes for 235/40R18 tire?

235/40R18 alternative has to be within 3% of the original tire's overall diameter to ensure safe drive and proper speedometer readings. Below is a list of 235/40R18 equivalent and plus sizes that are within the optimal characteristics and dimensions of the orignal tire size.

Keep in mind that different vehicles have different tire requirements. Passenger cars, SUVs, trucks, and high-performance vehicles each have specific types of tires that are engineered for their particular needs. When replacing tires on your vehicle, always refer to your vehicle's owner's manual for manufacturer recommendations on tire size, type, and other specifications.

Replacement Tire Size Tire Diameter Difference
P245/35R18 -2.5%
P235/40R18 0%
P245/40R18 1.2%
P225/45R18 2.2%
P225/40R18 -1.2%
245/40R18 1.2%
245/35R18 -2.5%
225/40R18 -1.2%
225/45R18 2.2%
245/35R19 1.6%
P235/35R19 0.3%
245/30R19 -2.2%
225/35R19 -0.6%
225/40R19 2.8%
235/35R19 0.3%
235/30R20 0.8%
245/30R20 1.7%
225/30R20 -0.2%

What wheels can 235/40R18 tire be mounted on?

235/40R18 tires are generally approved to be mounted on 8" to 9.5" wide wheels. The following wheel sizes can be used:

  • 18x8
  • 18x8.5
  • 18x9
  • 18x9.5

It is important to note that while a tire might physically fit on a wheel outside of the recommended widths, doing so can affect the tire's performance, handling, and wear. Always refer to your vehicle's manufacturer guidelines and the tire manufacturer's specifications for the best results.

235/40R18 Tire Size Comparison Chart

Below is a comparison chart where we compare 235/40R18 tire size with other popular sizes. Green indicates that new tire diameter is within the acceptable 3% of the original, while red warns that tire will adversely affect the vehicle's speedometer reading, handling characteristics, or clearance in the wheel well. We recommend to use the tire size comparison tool to ensure proper compatibility when switching to a new tire size.

Tire Size Comparison Tire Diameter Difference
235/40R18 vs 245/50R18 9%
235/40R18 vs P255/70R18 26.4%
235/40R18 vs P255/65R18 22.3%
235/40R18 vs 255/45R18 6.5%
235/40R18 vs P245/60R18 16.4%
235/40R18 vs 255/55R18 14.3%
235/40R18 vs P245/45R18 5%
235/40R18 vs P245/40R18 1.2%
235/40R18 vs 255/60R18 18.3%
235/40R18 vs 255/40R18 2.5%
235/40R18 vs P265/60R18 20.2%
235/40R18 vs P265/65R18 24.2%
235/40R18 vs 265/40R18 3.7%
235/40R18 vs 265/35R18 -0.3%
235/40R18 vs 245/55R18 12.7%
235/40R18 vs 265/65R18 24.2%
235/40R18 vs 245/60R18 16.4%
235/40R18 vs P275/35R18 0.6%
235/40R18 vs P265/70R18 28.5%
235/40R18 vs 255/35R18 -1.6%
235/40R18 vs P235/65R18 18.3%
235/40R18 vs P235/60R18 14.6%
235/40R18 vs 255/65R18 22.3%
235/40R18 vs 265/60R18 20.2%
235/40R18 vs LT275/65R18 26.4%
235/40R18 vs 265/70R18 28.5%
235/40R18 vs LT265/70R18 28.4%
235/40R18 vs 275/35R18 0.6%
235/40R18 vs 295/30R18 -1.6%
235/40R18 vs 275/40R18 5%
235/40R18 vs 285/60R18 23.9%
235/40R18 vs LT275/70R18 30.5%
235/40R18 vs LT305/70R18 37.1%
235/40R18 vs LT325/65R18 36.4%
235/40R18 vs 255/70R18 26.4%
235/40R18 vs P235/50R18 7.4%
235/40R18 vs P225/60R18 12.7%
235/40R18 vs LT285/75R18 37.2%
235/40R18 vs P225/55R18 9.3%
235/40R18 vs P225/45R18 2.2%
235/40R18 vs P225/40R18 -1.2%
235/40R18 vs P215/55R18 7.4%
235/40R18 vs 275/65R18 26.4%
235/40R18 vs 205/40R18 -3.7%
235/40R18 vs LT285/70R18 32.7%
235/40R18 vs 225/50R18 5.9%
235/40R18 vs LT285/65R18 28.4%
235/40R18 vs 225/60R18 12.7%
235/40R18 vs LT285/60R18 23.9%
235/40R18 vs LT265/65R18 24.3%
235/40R18 vs LT265/60R18 20.2%
235/40R18 vs 275/60R18 22%
235/40R18 vs 235/45R18 3.7%
235/40R18 vs 225/45R18 2.2%
235/40R18 vs LT295/70R18 34.9%
235/40R18 vs 215/40R18 -2.5%
235/40R18 vs 215/45R18 0.9%
235/40R18 vs LT325/60R18 31.3%
235/40R18 vs 215/50R18 4.3%
235/40R18 vs 215/55R18 7.4%
235/40R18 vs 225/35R18 -4.7%
235/40R18 vs LT305/65R18 32.4%
235/40R18 vs LT305/60R18 27.6%
235/40R18 vs 225/40R18 -1.2%
235/40R18 vs 215/35R18 -5.9%
235/40R18 vs P275/65R18 26.4%
235/40R18 vs 295/35R18 2.8%
235/40R18 vs 235/60R18 14.6%
235/40R18 vs 285/35R18 1.9%
235/40R18 vs 245/35R18 -2.5%
235/40R18 vs 245/45R18 5%
235/40R18 vs 235/55R18 10.9%
235/40R18 vs 285/30R18 -2.5%
235/40R18 vs 245/40R18 1.2%
235/40R18 vs 265/45R18 7.8%
235/40R18 vs 315/30R18 0.3%
235/40R18 vs 225/55R18 9.3%
235/40R18 vs 235/50R18 7.4%
235/40R18 vs 235/65R18 18.3%
235/40R18 vs 305/30R19 3.4%
235/40R18 vs 295/35R19 6.8%
235/40R18 vs 285/30R19 1.6%
235/40R18 vs 285/35R19 5.9%
235/40R18 vs 325/30R19 5.3%
235/40R18 vs 285/40R19 10.2%
235/40R18 vs P245/45R19 9%
235/40R18 vs P235/55R19 14.9%
235/40R18 vs P245/55R19 16.7%
235/40R18 vs P255/60R19 22.3%
235/40R18 vs 305/35R19 8.1%
235/40R18 vs 315/30R19 4.3%
235/40R18 vs 295/40R19 11.5%
235/40R18 vs 295/30R19 2.5%
235/40R18 vs 285/45R19 14.6%
235/40R18 vs 275/55R19 21.7%
235/40R18 vs 275/50R19 17.7%
235/40R18 vs 245/45R19 9%
235/40R18 vs 255/60R19 22.3%
235/40R18 vs 265/30R19 -0.3%
235/40R18 vs 235/35R19 0.3%
235/40R18 vs 265/35R19 3.7%
235/40R18 vs 265/40R19 7.8%
235/40R18 vs 235/45R19 7.8%
235/40R18 vs 265/45R19 11.8%
235/40R18 vs 265/50R19 16.1%
235/40R18 vs 245/35R19 1.6%
235/40R18 vs 255/55R19 18.3%
235/40R18 vs 235/50R19 11.5%
235/40R18 vs 245/50R19 13%
235/40R18 vs 245/55R19 16.7%
235/40R18 vs 255/30R19 -1.2%
235/40R18 vs 255/35R19 2.5%
235/40R18 vs 255/40R19 6.5%
235/40R18 vs 235/55R19 14.9%
235/40R18 vs 255/45R19 10.5%
235/40R18 vs 255/50R19 14.6%
235/40R18 vs 265/55R19 20.2%
235/40R18 vs 235/40R19 4%
235/40R18 vs 275/35R19 4.7%
235/40R18 vs 275/45R19 13.3%
235/40R18 vs 275/40R19 9%
235/40R18 vs 225/35R19 -0.6%
235/40R18 vs 225/45R19 6.2%
235/40R18 vs 225/40R19 2.8%
235/40R18 vs 225/55R19 13.3%
235/40R18 vs 245/40R19 5.3%
235/40R18 vs 275/30R19 0.6%
235/40R18 vs LT305/55R20 30.9%
235/40R18 vs 235/55R20 18.8%
235/40R18 vs 305/50R20 26.2%
235/40R18 vs 295/35R20 10.7%
235/40R18 vs 225/35R20 3.3%
235/40R18 vs 235/60R20 22.5%
235/40R18 vs LT295/65R20 38.3%
235/40R18 vs 245/30R20 1.7%
235/40R18 vs 215/45R20 8.8%
235/40R18 vs 255/55R20 22.2%
235/40R18 vs 245/35R20 5.4%
235/40R18 vs 305/40R20 16.6%
235/40R18 vs 235/50R20 15.3%
235/40R18 vs 295/25R20 1.7%
235/40R18 vs 235/40R20 7.9%
235/40R18 vs 245/60R20 24.3%
235/40R18 vs 235/35R20 4.2%
235/40R18 vs 235/30R20 0.8%
235/40R18 vs LT275/55R20 25.7%
235/40R18 vs LT275/60R20 29.9%
235/40R18 vs LT285/55R20 27.4%
235/40R18 vs 235/45R20 11.6%
235/40R18 vs LT325/60R20 39.2%
235/40R18 vs 315/35R20 12.9%
235/40R18 vs LT285/65R20 36.3%
235/40R18 vs 315/30R20 8.2%
235/40R18 vs LT295/55R20 29.1%
235/40R18 vs LT295/60R20 33.6%
235/40R18 vs 295/30R20 6.4%
235/40R18 vs 245/40R20 9.1%
235/40R18 vs 265/60R20 28.1%
235/40R18 vs LT265/60R20 28.1%
235/40R18 vs 305/35R20 11.9%
235/40R18 vs 305/30R20 7.3%
235/40R18 vs 275/30R20 4.5%
235/40R18 vs 295/45R20 20%
235/40R18 vs 295/40R20 15.3%
235/40R18 vs 275/35R20 8.5%
235/40R18 vs 285/50R20 23.1%
235/40R18 vs 285/45R20 18.4%
235/40R18 vs 285/40R20 14.1%
235/40R18 vs 285/35R20 9.8%
235/40R18 vs 275/40R20 12.9%
235/40R18 vs 285/30R20 5.4%
235/40R18 vs 275/60R20 29.9%
235/40R18 vs 275/55R20 25.6%
235/40R18 vs 275/45R20 17.2%
235/40R18 vs LT275/65R20 34.3%
235/40R18 vs LT285/60R20 31.8%
235/40R18 vs 245/45R20 12.9%
235/40R18 vs 245/50R20 16.9%
235/40R18 vs P275/60R20 29.9%
235/40R18 vs P275/55R20 25.6%
235/40R18 vs 255/30R20 2.6%
235/40R18 vs 255/35R20 6.4%
235/40R18 vs 255/40R20 10.4%
235/40R18 vs P255/50R20 18.4%
235/40R18 vs 255/45R20 14.4%
235/40R18 vs P245/50R20 16.9%
235/40R18 vs 255/50R20 18.4%
235/40R18 vs 255/60R20 26.2%
235/40R18 vs 265/30R20 3.6%
235/40R18 vs 265/40R20 11.6%
235/40R18 vs 265/45R20 15.7%
235/40R18 vs 265/50R20 20%
235/40R18 vs 265/35R20 7.6%
235/40R18 vs 275/50R20 21.6%

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