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Understanding Your Tire

Tire width

The width of your tire, in millimeters, measured from sidewall to sidewall.

Aspect ratio

This is the ratio of the tire’s cross-section to its width, expressed as a percentage. An aspect ratio of 70, for example, indicates that the tire’s height is 70% of its width.

Wheel diameter

The diameter (height) of the wheel in inches.
Your tyre’s load index tells you its maximum carrying capacity

Load index

Your tire’s load index tells you its maximum carrying capacity. It’s important to choose a replacement tire that fits with your manufacturer’s recommendations.

Load ratings and speed ratings should be looked at together when you choose a tire. You’ll find the load rating of your current tire on the sidewall, just beside the diameter.

The speed rating is the maximum speed a tyre can legally support

Speed Rating

The speed rating is the maximum legal speed for a tire when it is correctly inflated and in use under load.

You will find your tires speed rating printed on the sidewall, and represented by a letter. A tire with a speed rating of J, for example, has a maximum speed of 100 km/h.

When buying replacement tires it is essential to match their speed rating with the speed capabilities of your vehicle.

Check out the maximum speed allowed by inputting your speed index into the application.

Reading your tire

A truck tire’s sidewall markings tell everything about that tire. They describe exactly the size of the tire, its construction and its performance limits. Much of this is statutory information and has to meet international requirements.

In Europe, it is the European ECE-R54 regulations which are relevant and all tires for commercial vehicles operating within a speed range of 80 – 130 km/h carry a ‘Service Description’ which is placed close to the tire size marking.

Goodyear trailer tires produced for the Europe, Middle East and Africa carry the “FRT” marking on their sidewalls. “FRT” stands for “Free Rolling Tire” and is a legal marking according to the UNECE Regulation No. 54, which indicates that the tire is specifically designed and intended for the equipment of trailer axles and axles of motor vehicles other than front steering and all drive axles.

Therefore those trailer tires marked “FRT” should be used exclusively on trailer axles and should not be fitted in any other position Goodyear will not warrant and cannot be held accountable for any potential liability claim involving FRT tires fitted outside these recommendations.

The position of the major tire markings are as shown

  1. Tire Section width (mm or inches)
  2. Aspect ratio SH / SD Radial construction
  3. (R=Radial)
  4. Rim Diameter (inches)
  5. Load Index (Max. load per tire - single tire)
  6. Load Index (Max. load per tire - dual mounted)
  7. Speed Symbol
  8. Alternative load indices when used with alternative speed
  9. TWI - Tread Wear Indicator
  10. ECE Homologation number
  11. Date code (week, year)
  12. DOT Manufacturing Code
  13. Noise number - indicates that the tire conforms to ECE noise regulations