325/40R21 In Inches

What size tire is 325/40R21 in Inches?

The 325/40R21 equivalent to 31.2x12.8R21 in inches, as follow:

  • 31.2 inches (793mm) stand for the tire diameter, also referred to as the tire height
  • 12.8 inches (325mm) is the tire width, this may also know as the section width
  • 21 inches (533mm) represent the rim diameter or called the wheel diameter that can be mounted on.
InchesMetric
Tire Diameter31.2"793 mm
Tread Width12.8"325 mm
Rim Diameter21"533 mm
Sidewall Height5.1"130 mm
Circumference98"2489 mm
Revolutions647 revs/mile402 revs/km
tire diameter
12.8"
31.2"
Tire Side
Tire Circumference
98"
21"
5.1"
647 Revs/Mile

How tall is a 325/40R21 tire’s height?

The 325/40R21 has an overall diameter of 31.2 inches or 793 mm tall (measured from the outside edges of the wheel)

How wide is a 325/40R21 tire’s width?

The 325/40R21 has a width of 12.8 inches or 325 mm wide. This is the measurement of the tire at its thickest point, the distance between the outer sidewall’s widest point and the inner sidewall’s widest point. This physical width of the tire can change if the tire is mounted on a wheel slightly wider or narrower than the size indicated by the rim width.

What is a 325/40R21 tire sidewall height?

The 325/40R21 has a sidewall height of 5.1 inches or 130 mm tall. It’s measured from the rim to the outer edge of the tire.

What size rim do you need for 325/40R21?

The 325/40R21 tire has a size rim of 21 inches or 533 mm. This number represents the distance between the two bead seat areas where the tire is sealed onto the wheel.

How many revolutions for 325/40R21 per mile or kilometer?

The 325/40R21 performs 647 revolutions per mile or 402 revolutions per kilometer. Revolutions per mile indicate the number of times a tire revolves while it covers the distance of one mile/kilometer

How about 325/40R21 tire circumference?

The circumference of 325/40R21 is 98 inches or 2489 mm.

What’s wider or narrow than 325/40R21 is acceptable?

You can replace the 325/40R21 tires that are within ±3% of the overall tire diameter. In this case, it’s between 30.3 and 32.1 inches (769mm to 817 mm). Check our tire size chart here or the tire size calculator tool here to find your size.

*Disclaimer: The information provided on the tire size is for general informational purposes only. We recommend that you consult a certified tire specialist or National Highway Traffic Safety Administration (NHTSA) sets specific guidelines for tires used on vehicles.


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Jamie Hicks

Sullivan Kane

Tire Technician at TireSizesCalculator

Sullivan is a Tire Technician specializing in tire repair at TireSizesCalculator. With over 6 years of experience in the industry, Sullivan has become an expert in tire repair, maintenance & installation.



Tire Size Chart for 21" Wheels:

26″ Tire Diameter

27″ Tire Diameter

28″ Tire Diameter


29″ Tire Diameter

30″ Tire Diameter

31″ Tire Diameter

32″ Tire Diameter


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