bike tyre size chart load speed tyre rim etc

Understanding motorcycle tire sizes can be a bit confusing at first, but it’s crucial for ensuring you have the right tires for your bike. Motorcycle tire sizes are usually represented in a specific format that includes several key pieces of information: the tire’s width, aspect ratio, and rim diameter. Here’s a breakdown of how to read and understand these sizes:

1. Tire Width

Table of Contents

Example: 180/70ZR-16
What it means: The first number (180) indicates the tire’s width in millimeters. This is the measurement of the tire’s width from sidewall to sidewall when mounted on the proper width rim.

2. Aspect Ratio

Example: 180/70ZR-16
What it means: The second number (70) is the aspect ratio, which represents the height of the tire’s sidewall as a percentage of the tire’s width. In this case, the sidewall height is 70% of the 180 mm width.

3. Speed Rating and Construction

Example: 180/70ZR-16
What it means:
- The letter(s) before the rim diameter (Z in this case) is the speed rating. The speed rating indicates the maximum speed the tire can safely maintain. Common ratings include:
  - J: up to 62 mph
  - L: up to 75 mph
  - P: up to 93 mph
  - H: up to 130 mph
  - V: up to 149 mph
  - Z: over 149 mph
- The letter “R” indicates the tire’s construction type, which in this case is radial. If there is no letter, it usually indicates a bias-ply construction.

4. Rim Diameter

Example: 180/70ZR-16
What it means: The last number (16) indicates the diameter of the rim in inches that the tire is designed to fit.

5. Additional Markings

There might be additional markings and codes on a motorcycle tire that provide other information:

Load Index: This is a numerical code that corresponds to the maximum load the tire can carry at the speed indicated by its speed rating.
M/C: Indicates that the tire is for motorcycle use.
Tubeless (TL) or Tube Type (TT): Indicates whether the tire is designed for use with a tube or not.
Date Code: Tires also have a four-digit code indicating the week and year of manufacture (e.g., 2518 means the tire was made in the 25th week of 2018).

Examples of Motorcycle Tire Sizes

Example 1: 120/70ZR-17
- 120: Tire width in millimeters.
- 70: Aspect ratio (70% of 120 mm).
- ZR: Z-speed rating, radial construction.
- 17: Rim diameter in inches.

Example 2: 90/90-21
- 90: Tire width in millimeters.
- 90: Aspect ratio (90% of 90 mm).
- -21: Bias-ply construction (no R), rim diameter in inches.

Conversion to Metric Sizes

Sometimes, tires are marked with inch-based sizing, particularly on older or specialized motorcycles. An example is:

MT90-16
- M: Tire width code.
- T: Aspect ratio code.
- 90: Speed rating.
- 16: Rim diameter in inches.

Summary

By understanding these codes and markings, you can select the appropriate tires for your motorcycle, ensuring proper fit, performance, and safety. Always refer to your motorcycle’s owner manual for the recommended tire sizes and specifications.

R17 Means RIM Size

Load Index weight bearable

Speed index (supported speed)