Motorcycle Tyre Size Calculator : Deciphering Tire Dimensions

Our handy motorcycle tire size calculator helps riders compare tire sizes including tire’s width, aspect ratio, construction type, and rim diameter.

For example, a tire size of 120/70-17 can be broken down as follows:

• 120: Width of the tire in millimeters
• 70: Aspect ratio (height as a percentage of width)
• 17: Rim diameter in inches

Motorcycle Tyre Size Calculator

Original Size	New Size	Diameter Difference	Circumference Difference	Speedometer Error
120/70-17	120/80-17	+25.4 mm	+79.8 mm	-3.2%
180/55-17	190/50-17	-10.2 mm	-32.0 mm	+1.3%
110/80-18	100/90-18	+5.1 mm	+16.0 mm	-0.6%
150/70-16	160/60-16	-20.3 mm	-63.8 mm	+2.6%
130/90-16	140/90-16	+10.2 mm	+32.0 mm	-1.5%
90/90-21	100/90-21	+10.2 mm	+32.0 mm	-1.5%
150/80-16	160/70-16	-15.2 mm	-47.8 mm	+1.9%
120/60-17	130/60-17	+10.2 mm	+32.0 mm	-1.5%
140/80-17	150/70-17	-12.7 mm	-39.9 mm	+2.1%
100/90-19	110/80-19	+11.4 mm	+35.8 mm	-1.7%

Common Motorcycle Tire Sizes

Motorcycle Type	Front Tire Size	Rear Tire Size
Sport	120/70-17	180/55-17
Cruiser	100/90-19	150/80-16
Adventure	90/90-21	150/70-17
Touring	120/70-18	180/55-17
Dirt Bike	80/100-21	110/100-18
Cafe Racer	100/90-18	130/80-17
Chopper	120/70-21	150/70-18
Scooter	120/70-12	130/70-12
Enduro	90/90-19	140/80-18
Dual-Sport	110/80-19	140/80-17
Track Bike	120/60-17	190/50-17
Electric Motorcycle	120/70-14	150/70-14

Motorcycle Tire Size Conversion Formula

The conversion formula for motorcycle tires involves several key measurements:

• Tire Width: Measured in millimeters
• Aspect Ratio: Height of the sidewall as a percentage of width
• Rim Diameter: Typically measured in inches

To calculate the overall tire diameter:

Overall Diameter = (2 × Tire Width × Aspect Ratio ÷ 100) + (Rim Diameter × 25.4)

For a 180/55-17 tire:

• Tire Width: 180 mm
• Aspect Ratio: 55%
• Rim Diameter: 17 inches

Overall Diameter = (2 × 180 × 55 ÷ 100) + (17 × 25.4)
                 = 198 + 431.8
                 = 629.8 mm

How to find motorcycle tire size?

• Locate the tire sidewall: The size is molded into the rubber.
• Identify the code: Look for a series of numbers and letters, e.g., 180/55ZR17.
• Decode the information:
  • 180: Tire width in millimeters
  • 55: Aspect ratio
  • ZR: Speed rating and radial construction
  • 17: Rim diameter in inches

A tire marked 160/60R18 translates to:

• Width: 160 mm
• Aspect Ratio: 60% of width
• Construction: Radial
• Rim Diameter: 18 inches

How wide is a 90 motorcycle tire?

A 90 motorcycle tire refers to a tire with a width of 90 millimeters (approximately 3.54 inches).

Consider a tire size of 90/90-18:

• 90 mm: Width
• 90%: Aspect ratio (height is 90% of 90 mm, which is 81 mm)
• 18 inches: Rim diameter

What is 3.00 in tire size?

The designation “3.00” in a motorcycle tire size typically refers to the tire width in inches. This older sizing system is still used for some classic or vintage motorcycles.

A tire size of 3.00-18 would indicate:

• Width: 3.00 inches (approximately 76.2 mm)
• Rim Diameter: 18 inches

To convert this to the metric system:

3.00 inches × 25.4 mm/inch = 76.2 mm

Sources / References

• Motorcycle Safety Foundation: https://www.msf-usa.org/
• RevZilla: https://www.revzilla.com/common-tread/how-to-read-motorcycle-tire-sizes

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