255/40R13 Tire Size in Inches and Millimeters

Understanding the 255/40R13 Tire Size

The tire size 255/40R13 is a specific designation that provides important information about the tire's dimensions and construction. Here's a breakdown of what each part of this size means:

• 255 - This is the tire's width in millimeters. It represents the section width of the tire from sidewall to sidewall.

• 40 - This is the aspect ratio, which is the height of the tire's sidewall expressed as a percentage of the tire's width. In this case, the sidewall height is 40% of the width.

• R - This indicates that the tire has radial construction, which is the most common type of tire construction today.

• 13 - This is the diameter of the wheel in inches that the tire is designed to fit.

How to Convert 255/40R13 Into Inches

Converting tire dimensions from metric to imperial units involves a few straightforward calculations. Here's how to convert the 255/40R13 tire size:

• Width Conversion: The width of 255 mm can be converted to inches by dividing by 25.4 (since 1 inch = 25.4 mm).
  Calculation: 255 mm ÷ 25.4 = 10.04 inches

• Sidewall Height Calculation: The sidewall height is 40% of the width. First, calculate the sidewall height in mm, then convert to inches.
  Calculation: 255 mm × 0.40 = 102 mm
  102 mm ÷ 25.4 = 4.02 inches

• Overall Diameter Calculation: The overall diameter is the sum of the wheel diameter and twice the sidewall height (since there are two sidewalls, top and bottom).
  Calculation: (4.02 inches × 2) + 13 inches = 21.04 inches

Detailed Conversion Table

Quick Conversion Tips

To quickly convert tire dimensions, remember that 1 inch equals 25.4 mm. For a rough estimation, you can use 10 mm as approximately 0.4 inches. Always ensure to double-check calculations for accuracy, especially when considering fitment for a specific vehicle.

Technical Specifications and Dimensions

• Width: 255 mm (10.04 inches)

• Aspect Ratio: 40

• Wheel Diameter: 13 inches

• Overall Diameter: 21.04 inches

• Load Index: Typically varies, check specific tire model

• Speed Rating: Typically varies, check specific tire model

• Tread Depth: Typically varies, check specific tire model

• Temperature and Traction Ratings: Typically varies, check specific tire model

Compatible Vehicles for 255/40R13

The 255/40R13 tire size is often used in specific types of vehicles, particularly those that require a lower profile tire for performance purposes. Here are some common applications:

• Classic Sports Cars: Certain models from the 1970s and 1980s may use this size for performance enhancements.

• Compact Cars: Some compact and subcompact cars may use this size for improved handling.

• Specific Models: Check with the vehicle manufacturer or a tire specialist to confirm compatibility for specific years and models.

Important fitment considerations include ensuring the tire does not interfere with the vehicle's suspension or bodywork and that it meets the load and speed requirements of the vehicle.

Size Comparison and Alternatives

When considering alternative tire sizes, it's important to stay within a 3% difference in overall diameter to maintain vehicle performance and safety. Here are some potential alternatives:

• Alternative Size 1: 245/45R13 - Offers a slightly wider profile with a similar overall diameter.

• Alternative Size 2: 265/35R13 - Provides a lower profile with a comparable overall diameter.

Always consult with a tire professional to ensure any alternative size is suitable for your specific vehicle.

FAQ Section

What is the recommended tire pressure for 255/40R13 tires?

The recommended tire pressure can vary based on the vehicle and tire manufacturer. Generally, it ranges from 30 to 35 PSI (207 to 241 kPa). Always refer to the vehicle's owner manual or the tire placard for the exact pressure specifications.

Can I use a different tire size than 255/40R13?

Using a different tire size is possible, but it requires careful consideration of the vehicle's specifications and the 3% rule for overall diameter. Consult with a tire specialist to explore compatible alternatives that maintain safety and performance.

What is the width and height of a 255/40R13 tire?

The width of a 255/40R13 tire is 255 mm (10.04 inches), and the sidewall height is 102 mm (4.02 inches). These measurements are crucial for understanding how the tire will fit and perform on your vehicle.

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