235/55R20 Tire Size in Inches & Millimeters

Tire size “235/55R20” 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 235/55R20 to inches, you must know what these numbers represent.

So let us know 235/55R20 in simple words:

First number “235” indicates the tire’s width in millimeters.
Second number “55” 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 235/55R20 to inches, it can be concluded that the width of the tire will be approximately 9.3 inches ( 235 mm= 9.3 in), and the sidewall height will be approximately 5.1 inches (55% of 9.3 inches = 5.1 inches).

How to convert 235/55R20 into Inches (imperial)?

To convert tire size 235/55R20 to inches (Imperial) –

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

  • 235 millimeters/25.4 = approximately 9.3 inches
    So, the width of the tire is approximately 9.3 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 = 9.3 inches * 55/100 = approximately 5.1 inches
    So, the tire sidewall height is approximately 5.1 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 “235/55R20” in inches (imperial) is approximately:

  • Width: 9.3 inches
  • Sidewall Height: 5.1 inches
  • Rim Diameter: 20 inches

How to convert 235/55R20 into Millimeters (metric)?

To convert the tire size 235/55R20 into millimeters (metric) –

1. Width Conversion: The first number in the tire size, “235“, represents the tire’s width in millimeters. Since it’s already in millimeters, there’s no need for conversion.

  • Width: 235millimeters

2. Aspect Ratio Calculation: The second number “55” 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 = 235 millimeters * 55 / 100 = 129 mm millimeters
    So, the tire’s sidewall height is approximately 129 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 “235/55R20” in millimeters (metric) is approximately:

  • Width: 235 mm
  • Sidewall Height: 129 mm
  • Rim Diameter: 508 mm

Alternate Tire Size of 235/55R20 For replacement

Tire Size Overall Diameter Difference
235/50R20 29.3″ (744 mm) -2.9%
295/40R20 29.3″ (744 mm) -2.9%
235/45R21 29.3″ (745 mm) -2.7%
265/40R21 29.3″ (745 mm) -2.7%
265/35R22 29.3″ (745 mm) -2.7%
265/45R20 29.4″ (746 mm) -2.6%
305/35R21 29.4″ (747 mm) -2.5%
315/30R22 29.5″ (749 mm) -2.2%
275/35R22 29.6″ (751 mm) -2%
305/40R20 29.6″ (752 mm) -1.8%
275/40R21 29.6″ (753 mm) -1.7%
315/35R21 29.6″ (753 mm) -1.7%
245/45R21 29.6″ (753 mm) -1.7%
245/50R20 29.7″ (754 mm) -1.6%
275/45R20 29.8″ (756 mm) -1.3%
285/35R22 29.9″ (759 mm) -0.9%
285/40R21 30″ (761 mm) -0.7%
255/45R21 30″ (763 mm) -0.4%
255/40R22 30″ (763 mm) -0.4%
255/50R20 30.1″ (764 mm) -0.3%
285/45R20 30.1″ (764 mm) -0.3%
295/35R22 30.1″ (765 mm) -0.1%
295/40R21 30.3″ (769 mm) 0.4%
265/45R21 30.4″ (771 mm) 0.7%
265/40R22 30.4″ (771 mm) 0.7%
305/35R22 30.4″ (773 mm) 0.9%
295/45R20 30.5″ (774 mm) 1%
265/50R20 30.5″ (774 mm) 1%
275/40R22 30.7″ (779 mm) 1.7%
315/35R22 30.7″ (779 mm) 1.7%
275/45R21 30.7″ (781 mm) 2%
305/45R20 30.8″ (782 mm) 2.1%
275/50R20 30.9″ (784 mm) 2.3%
315/40R21 30.9″ (785 mm) 2.5%
285/40R22 31″ (787 mm) 2.7%
325/35R22 31″ (787 mm) 2.7%
255/55R20 31″ (788 mm) 2.9%

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