LT315/70R20 Tire Size in Inches & Millimeters

Tire size “315/70R20” indicates your vehicle’s specifications based on tire width, aspect ratio, height, tire construction, diameter, radial and inches. These tire size numbers represent our tire sizes in both Metric (in millimeters) and Imperial (in inches) units of measurement to help find the correct tire size for your vehicle.

To convert tire size LT315/70R20 to inches, you must know what these numbers represent.

So let us know LT315/70R20 in simple words:

First number “315” indicates the tire’s width in millimeters.
Second number “70” refers to the aspect ratio, which is the height of the tire’s sidewall as a percentage of its width.
Third number “R20” refers to a tire that is designed to fit a 20-inch diameter rim.

Therefore, when converting the tire size LT315/70R20 to inches, it can be concluded that the width of the tire will be approximately 12.4 inches ( 315 mm= 12.4 in), and the sidewall height will be approximately 8.7 inches (70% of 12.4 inches = 8.7 inches).

How to convert LT315/70R20 into Inches (imperial)?

To convert tire size LT315/70R20 to inches (Imperial) –

1. Width conversion: To convert it to inches, you can use a conversion factor of approximately 25.4 millimeters per inch.

  • 315 millimeters/25.4 = approximately 12.4 inches
    So, the width of the tire is approximately 12.4 inches.

2. Aspect Ratio Calculation: To calculate sidewall height in inches, you can use the tire width (from Step 1) and the aspect ratio:

  • Sidewall Height = Width (in inches) * Aspect Ratio / 100
  • Sidewall Height = 12.4 inches * 70/100 = approximately 8.7 inches
    So, the tire sidewall height is approximately 8.7 inches.

3. Rim Diameter: The “R” in the tire size stands for “radial construction” and the last number “20” indicates the rim diameter in inches. In this case, it’s already in inches.
So, the converted tire size “LT315/70R20” in inches (imperial) is approximately:

  • Width: 12.4 inches
  • Sidewall Height: 8.7 inches
  • Rim Diameter: 20 inches

How to convert LT315/70R20 into Millimeters (metric)?

To convert the tire size LT315/70R20 into millimeters (metric) –

1. Width Conversion: The first number in the tire size, “315“, represents the tire’s width in millimeters. Since it’s already in millimeters, there’s no need for conversion.

  • Width: 315millimeters

2. Aspect Ratio Calculation: The second number “70” is the aspect ratio, representing the tire’s sidewall height as a percentage of its width. To calculate the sidewall height in millimeters, you can use the tire’s width (from step 1) and the aspect ratio:

  • Sidewall height = Width (in millimeters) * Aspect Ratio / 100
  • Sidewall height = 315 millimeters * 70 / 100 = 221 mm millimeters
    So, the tire’s sidewall height is approximately 221 mm millimeters.

3. Rim Diameter: The “R” in the tire size stands for “radial construction” and the last number, “20” indicates the rim diameter in inches. To convert this to millimeters, you can use the conversion factor of approximately 25.4 millimeters per inch.

  • Rim diameter = 20 inches * 25.4 millimeters per inch = 508 mm millimeters
    So, the rim diameter is approximately 508 mm millimeters.

So, the converted tire size “LT315/70R20” in millimeters (metric) is approximately:

  • Width: 315 mm
  • Sidewall Height: 221 mm
  • Rim Diameter: 508 mm

Alternate Tire Size of LT315/70R20 For replacement

Tire Size Overall Diameter Difference
335/55R22 36.5″ (927 mm) -2.4%
355/60R20 36.8″ (934 mm) -1.7%
245/75R22.5 37″ (940 mm) -1.1%
235/80R22.5 37.3″ (948 mm) -0.2%
325/60R22 37.4″ (949 mm) -0.1%

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