Tire Size 33×12.5r20 in Metric

Off-road enthusiasts often search for the perfect tire size to balance traction, ground clearance, and performance. To better understand this tire size, it’s essential to explore the measurements in metric units. This article will discuss the 33×12.50R20 tire size and its metric equivalent.

33×12.50r20 in inches

This table provides a breakdown of the 33×12.50R20 tire size in inches, helping you to better understand its features and metrics.

Feature Metric
Diameter 33.0″
Width 12.5″
Wheel 20″ x 8.5-11
Sidewall 6.5″
Circumference 103.6″
Revs/Mile 611

Understanding Tire Metric
Tire sizes can be expressed using different units of measurement. In the United States, tire sizes are often displayed in inches, while the rest of the world uses the metric system. The 33×12.50r20 tire size is an example of a measurement expressed in inches. This notation consists of three parts:

  • 33 – The overall diameter of the tire, measured in inches.
  • 12.50 – The width of the tire, also measured in inches.
  • 20 – The diameter of the wheel the tire is designed to fit, measured in inches.

Replacement Tire Sizes
It is important to ensure that the overall diameter of the new tires is no more than 3% larger or smaller than that of the original tires.

Tire Size Overall Diameter Difference
275/55R20 31.9″ (810 mm) -2.9%
255/60R20 32″ (814 mm) -2.4%
305/50R20 32″ (814 mm) -2.4%
285/55R20 32.4″ (822 mm) -1.4%
315/50R20 32.4″ (824 mm) -1.2%
265/60R20 32.5″ (826 mm) -1%
295/55R20 32.8″ (832 mm) -0.2%
275/60R20 33″ (838 mm) 0.5%
305/55R20 33.2″ (844 mm) 1.2%
375/45R20 33.3″ (846 mm) 1.4%
285/60R20 33.5″ (850 mm) 1.9%

Converting to Metric
We need to convert the inch measurements into millimeters to understand this tire size in metric measurements. The conversion factor for inches to millimeters is 25.4, meaning you can multiply each measurement by 25.4 to obtain the metric equivalent.

  • 33 inches (overall diameter) x 25.4 = 838.2 millimeters
  • 12.50 inches (width) x 25.4 = 317.5 millimeters
  • 20 inches (wheel diameter) x 25.4 = 508 millimeters

Now, we have the metric measurements for the 33×12.50r20 tire size: 838.2×317.5×508 mm. However, the metric tire size notation typically used worldwide is slightly different. It follows this format: [Width]/[Aspect Ratio]R[Wheel Diameter].

Tire Width
Tire width refers to measuring the width of a tire in millimeters from sidewall to sidewall when the tire is mounted and inflated on a rim. The width of the tire is already in millimeters (317.5 mm).

Aspect Ratio
To calculate the aspect ratio, we need to determine the height of the tire’s sidewall. Since we know the overall diameter (838.2 mm) and wheel diameter (508 mm), we can subtract the wheel diameter from the overall diameter and divide the result by 2. Sidewall Height = (838.2 – 508) / 2 = 165.1 mm

The aspect ratio is the percentage of the tire width that represents the sidewall height. To find the aspect ratio, divide the sidewall height by the tire width and multiply by 100. Aspect Ratio = (165.1 / 317.5) x 100 = 52 (rounded to the nearest whole number)

Wheel Diameter
Wheel diameter refers to the measurement of the diameter of the wheel, including the rim and the tire, in inches. The wheel diameter is already in millimeters (508 mm).

If we were to convert the tire size to the metric system, the equivalent size would be 318/52r20. However, this size may not be readily available in the market since it is not a standard metric tire size. Metric tire sizes are rounded to the nearest 5 millimeters for width and the nearest whole number for the aspect ratio.

Finding a Close Metric Equivalent
The nearest metric equivalent to the 33×12.50r20 tire size, considering the standard metric sizes available, is 325/50r20. This size has the following dimensions:

  • Width: The 325/50r20 tire has a width of 325 mm, which is 7.5 mm wider than the 33×12.50r20 tire. The slightly wider tire may provide better traction in certain off-road conditions.
  • Aspect Ratio: The aspect ratio of the 325/50r20 tire is 50, slightly lower than the 52 aspect ratio calculated for the 33×12.50r20 tire. This difference means the 325/50r20 tire has a slightly shorter sidewall than the 33×12.50r20 tire.
  • Wheel Diameter: The 325/50r20 tire is designed for a 20-inch (508 mm) wheel, which is the exact wheel diameter of the 33×12.50r20 tire. This similarity ensures compatibility with the vehicle’s existing wheels.

While the 325/50r20 tire is not an exact match to the 33×12.50r20 tire in terms of dimensions, it is the closest metric equivalent that maintains the same wheel diameter. The minimal width and aspect ratio differences should not significantly impact the vehicle’s performance or handling characteristics.

Before opting for the 325/50r20 tire size as a replacement for the 33×12.50r20, check your vehicle’s owner’s manual and a tire professional to ensure compatibility and safety. Factors such as load capacity, speed rating, and suspension setup should also be considered when selecting a tire size for your off-road vehicle.

What Size Rim Fits A 33×12.50r20?

A 33×12.50R20 tire is designed to fit a 20-inch diameter rim. The width of the rim should also be considered to ensure a proper fit. For a 12.50-inch (317.5 mm) wide tire like the 33×12.50r20, a rim width between 8.5 and 11 inches (approximately 216-280 mm) is typically recommended.

It is important to note that the ideal rim width can vary depending on the specific tire model and the manufacturer’s recommendations. Always consult the tire manufacturer’s guidelines or a tire professional to ensure proper fitment and safe operation.

Leave a Comment

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

Scroll to Top