P145/80R12 Tire Size in Inches & Millimeters

Tire size “145/80R12” 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 P145/80R12 to inches, you must know what these numbers represent.

So let us know P145/80R12 in simple words:

First number “145” indicates the tire’s width in millimeters.
Second number “80” refers to the aspect ratio, which is the height of the tire’s sidewall as a percentage of its width.
Third number “R12” refers to a tire that is designed to fit a 12-inch diameter rim.

Therefore, when converting the tire size P145/80R12 to inches, it can be concluded that the width of the tire will be approximately 5.7 inches ( 145 mm= 5.7 in), and the sidewall height will be approximately 4.6 inches (80% of 5.7 inches = 4.6 inches).

How to convert P145/80R12 into Inches (imperial)?

To convert tire size P145/80R12 to inches (Imperial) –

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

  • 145 millimeters/25.4 = approximately 5.7 inches
    So, the width of the tire is approximately 5.7 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 = 5.7 inches * 80/100 = approximately 4.6 inches
    So, the tire sidewall height is approximately 4.6 inches.

3. Rim Diameter: The “R” in the tire size stands for “radial construction” and the last number “12” indicates the rim diameter in inches. In this case, it’s already in inches.
So, the converted tire size “P145/80R12” in inches (imperial) is approximately:

  • Width: 5.7 inches
  • Sidewall Height: 4.6 inches
  • Rim Diameter: 12 inches

How to convert P145/80R12 into Millimeters (metric)?

To convert the tire size P145/80R12 into millimeters (metric) –

1. Width Conversion: The first number in the tire size, “145“, represents the tire’s width in millimeters. Since it’s already in millimeters, there’s no need for conversion.

  • Width: 145millimeters

2. Aspect Ratio Calculation: The second number “80” 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 = 145 millimeters * 80 / 100 = 116 mm millimeters
    So, the tire’s sidewall height is approximately 116 mm millimeters.

3. Rim Diameter: The “R” in the tire size stands for “radial construction” and the last number, “12” 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 = 12 inches * 25.4 millimeters per inch = 305 mm millimeters
    So, the rim diameter is approximately 305 mm millimeters.

So, the converted tire size “P145/80R12” in millimeters (metric) is approximately:

  • Width: 145 mm
  • Sidewall Height: 116 mm
  • Rim Diameter: 305 mm

Alternate Tire Size of P145/80R12 For replacement

Tire Size Overall Diameter Difference
135/80R12 20.5″ (521 mm) -3%
165/50R14 20.6″ (522 mm) -2.8%
175/55R13 20.6″ (522 mm) -2.8%
155/70R12 20.6″ (523 mm) -2.6%
155/55R14 20.7″ (526 mm) -2%
165/60R13 20.8″ (528 mm) -1.7%
215/40R14 20.8″ (528 mm) -1.7%
125/80R13 20.9″ (530 mm) -1.3%
175/50R14 20.9″ (532 mm) -0.9%
155/65R13 20.9″ (532 mm) -0.9%
195/45R14 20.9″ (532 mm) -0.9%
225/45R13 20.9″ (532 mm) -0.9%
125/70R14 20.9″ (532 mm) -0.9%
185/55R13 21″ (534 mm) -0.6%
255/35R14 21″ (534 mm) -0.6%
255/40R13 21″ (534 mm) -0.6%
145/70R13 21″ (534 mm) -0.6%
225/40R14 21.1″ (536 mm) -0.2%
205/50R13 21.1″ (536 mm) -0.2%
165/70R12 21.1″ (537 mm) 0%
145R12 21.1″ (537 mm) 0%
165/55R14 21.2″ (538 mm) 0.2%
205/45R14 21.3″ (540 mm) 0.6%
175/60R13 21.3″ (540 mm) 0.6%
185/50R14 21.3″ (542 mm) 0.9%
145/65R14 21.4″ (544 mm) 1.3%
195/55R13 21.4″ (544 mm) 1.3%
165/65R13 21.4″ (544 mm) 1.3%
215/50R13 21.5″ (546 mm) 1.7%
135/80R13 21.5″ (546 mm) 1.7%
155/70R13 21.6″ (548 mm) 2%
185/60R13 21.7″ (552 mm) 2.8%
155/80R12 21.8″ (553 mm) 3%
155R12 21.8″ (553 mm) 3%

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