Fitment Help

Motorcycle Tyre Fitment Guide

Choosing the correct tyre sizes is essential for your safety, handling, braking performance, and motorcycle compliance on Australian roads and tracks. Motorcycle tyres come in various sizing standards, from modern metric designations to vintage imperial and alphanumeric codes. This guide will help you understand tyre markings before ordering.

How to Read a Motorcycle Tyre Size

You will typically find tyre specifications printed clearly on the sidewall of your existing tyres. Here is how to decode the most common sizing formats:

  • Modern Metric Radial (e.g. 120/70ZR17 or 180/55ZR17):
    • 120 or 180: The nominal section width of the tyre in millimetres across its widest point.
    • 70 or 55: The aspect ratio, meaning the tyre sidewall height is 70% or 55% of the section width.
    • ZR: Indicates a high-speed radial construction (Z represents high speed capability; R denotes radial plies).
    • 17: The rim diameter in inches that the tyre is designed to fit.
  • Off-Road & Dirt Bike Metric (e.g. 80/100-21):
    • 80: The width in millimetres.
    • 100: The aspect ratio (height equals 100% of width).
    • - (Hyphen): Indicates bias-ply or cross-ply construction.
    • 21: Suits a 21-inch front off-road rim.
  • Traditional Imperial / Classic (e.g. 3.00-10 or 3.50-8):
    • 3.00 or 3.50: The cross-section width (and approximately matching height) in inches. Common on small-wheel scooters, mopeds, and vintage mini-bikes.
    • 10 or 8: Fits a 10-inch or 8-inch rim diameter.
  • Alphanumeric Cruiser / Touring (e.g. MT90B16):
    • M: Designates motorcycle tyre use.
    • T: Tyre width code (T corresponds to approximately 130mm section width).
    • 90: Aspect ratio percentage (height is 90% of width).
    • B: Belted bias-ply construction.
    • 16: Fits a 16-inch rim. Often seen on heavy American cruisers and custom builds.

Front vs Rear Tyres

Motorcycle front and rear tyres perform completely different roles. Front tyres are engineered for directional steering precision, turning agility, and heavy braking loads. Rear tyres are wider and built to transfer engine drive force, resist acceleration wear, and provide straight-line stability.

Always verify whether a tyre is marked Front, Rear, or Universal. Directional arrows also indicate the correct rotation direction, which is critical for tread water displacement and internal ply strength.

Tube Type (TT) vs Tubeless (TL)

Pay close attention to whether your wheels require an inner tube:

  • Tubeless (TL): Designed for sealed, tubeless alloy or specialised airtight spoked rims. The tyre bead seats airtight directly against the rim edge.
  • Tube Type (TT): Requires a separate inner tube to hold air, standard for traditional wire-spoked wheels found on dirt bikes, dual-sport machines, and classic motorcycles.

Load Index & Speed Rating

Following the tyre dimensions, you will find a number and letter code, such as 58W or 73W:

  • Load Index (e.g. 58 or 73): A numerical code indicating the maximum load carrying capacity of the tyre at maximum air pressure (e.g. 58 = 236 kg, 73 = 365 kg). Never fit a tyre with a lower load index than specified on your motorcycle tyre placard.
  • Speed Rating (e.g. P, S, H, V, W): A letter code indicating the maximum speed the tyre can safely sustain under its designated load (e.g. H = up to 210 km/h, W = up to 270 km/h).

Modified Wheels & Aftermarket Rims

If your bike has modified wheels, always use the sizes on your actual tyres rather than relying solely on the original factory motorcycle handbook or VIN lookup. Aftermarket swingarms, wide-wheel conversions, supermoto rim setups, or custom spoke builds frequently change the required rim diameter and tyre profile.

Need Fitment Assistance? How to Ask Us

If you are unsure of the right compound, tread pattern, or sizing for your riding style, our team is happy to assist. Send an enquiry through our contact channels with the following details:

  • Motorcycle Make, Model, and Build Year: (e.g. Yamaha MT-09 2021)
  • Actual Sizes on Fitted Tyres: Both front and rear sidewall markings.
  • Wheel Specifications: Spoked or cast alloy, tube type or tubeless, stock or modified.
  • Riding Style & Intended Use: Daily commuting, highway touring, weekend track days, or off-road adventure.