# Tire Size 33×12.5r18 in Metric

Have you ever looked at the side of a tire and wondered what those seemingly cryptic numbers mean? Here’s one example that’s sure to catch your attention: the 33×12.5r18 tire size. At first glance, it seems like a code waiting to be deciphered. Let’s unravel the mystery together.

Dimension Breakdown
Unraveling the code “33×12.5r18” lets us understand the dimensions and features of the tire.

• The first number, “33”, stands for the tire’s overall diameter in inches. This means from one end of the tire to the other, and it measures 33 inches.
• The “12.5” that follows is the tire’s width, also in inches. So, the part of the tire that touches the road, often called the footprint, measures 12.5 inches across.
• Next, the “r” stands for radial, indicating the type of tire construction. In a radial tire, the cord plies are arranged at 90 degrees to the direction of travel, providing excellent durability and flexibility.
• Finally, “18” represents the wheel’s diameter, which means the wheel size the tire should be mounted on.

### 33×12.5r18 in inches

FeatureMetric
Tire Diameter33.0″
Tire Section Width12.5″
Rim Width Range18″ x 8.5-11″
Sidewall Height7.5″
Circumference103.6″
Revs/Mile611

Conversion Process
Let’s now turn to the conversion process, transforming these imperial units to metric.

• Overall Diameter: Multiply the inches by 25.4 to convert them to millimeters. So, for a 33-inch tire, the overall diameter in millimeters is 33 x 25.4 = 838.2 mm.
• Tire Width: The tire width is converted by multiplying 12.5 x 25.4, giving us 317.5 mm.
• Wheel Diameter: The same rule applies, with 18 x 25.4 providing a wheel diameter of 457.2 mm.
• Sidewall Height: Calculated as the difference between the overall diameter and the wheel diameter, then divided by 2 (since the tire consists of two sidewalls, top and bottom). So, (838.2 – 457.2) / 2 = 190.5 mm.
• Aspect Ratio: A ratio of the height of the tire’s cross-section to its width, expressed as a percentage. It’s calculated as (Sidewall Height / Tire Width) x 100. So, (190.5 / 317.5) x 100 = approximately 60%.

## 33×12.5r18 in Metric

The tire dimension expressed as 33×12.5r18 can be roughly transposed into metric system notation as 318/60r18, though it’s worth noting that this specific size is rarely seen in commercial outlets. While exact metric equivalents may not always exist for every tire size, you can find a close match.

For the 33×12.5r18 tire, a close metric equivalent is 315/60R18. This indicates a width of 315 mm, an aspect ratio of 60% (indicating the sidewall height is 60% of the tire’s width), and a wheel diameter of 18 inches.

Practical Applications
The 33×12.5r18 tire size is trendy among off-road enthusiasts and is often seen on 4×4 trucks and SUVs. Their larger diameter and width provide more ground clearance and better traction on uneven terrains. They can easily tackle obstacles such as rocks, mud, and sand, making them a favorite for off-roading adventures.

For instance, the Ford F-150 Raptor, a vehicle celebrated for its off-road prowess, often comes equipped with 33×12.5r18 tires. Due to their size, these tires can handle the rugged terrains that the Raptor is often put through.

#### How tall is a 33×12.5R18 tire?

The “33” in 33×12.5R18 represents the overall diameter of the tire, so it is 33 inches tall. To convert inches to millimeters, you multiply by 25.4.

• 33 inches * 25.4 = 838.2 mm

So, a 33×12.5R18 tire is approximately 838.2 millimeters tall.

#### How wide is a 33×12.5R18 tire?

The “12.5” in 33×12.5R18 represents the width of the tire, so it is 12.5 inches wide. Again, to convert inches to millimeters, you multiply by 25.4.

• 12.5 inches * 25.4 = 317.5 mm

So, a 33×12.5R18 tire is approximately 317.5 millimeters wide.

#### What size rim fits a 33×12.5R18 tire?

The “18” in 33×12.5R18 represents the rim diameter in inches the tire is designed to fit. So, this tire would fit an 18-inch rim. To convert this to millimeters:

• 18 inches * 25.4 = 457.2 mm

So, a 33×12.5R18 tire is designed to fit on a rim approximately 457.2 millimeters in diameter.

Summary
The world of tire sizes, like 33×12.5r18, is more than just a bunch of numbers and letters. They hold key information about a tire’s size, design, and function. By understanding their breakdown, conversions to metric, and practical applications, we can better appreciate their role in our vehicles’ performance.

Whether you’re an off-road enthusiast looking for the perfect tire, or just someone intrigued by those ‘cryptic’ numbers, this article has given you a newfound understanding and appreciation for tire sizes. Remember, every number and letter has a story to tell!

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