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Basic Tyre Knowledge

Basic Tyre Knowledge

How to Read Tire Size

Nominal section width (mm)

This refers to the width of the tire excluding design and lettering on the sidewall, etc. *Does not include rim guard.

Aspect ratio (series,%)

This figure indicates the ratio of a tire’s heigh.

Aspect ratio(%)= Tire height÷tire width×100

Construction code

“R” stands for radial structure.

Nominal rim diameter (inches)

Refers to the diameter of the wheel rim suitable for the tire. The term “tire’s inner diameter” is also used.

Load Index (LI)

An index expressing the maximum load permitted for a tire under established conditions.

Speed symbol

This indicates the maximum permissible speed in symbols under established conditions.

Speed category (ZR: over240km/h)

Nominal outside diameter (inches)

Nominal section width (inches)

Load Index: Single/Dual

C: Commercial vehicle

Complies with ETRTO(European tire regulations).

P: Passenger car tire

Complies with TRA(North American tire regulations).

LT: Light Truck

Complies with JATMA(Japanese tire regulations) or TRA(North American tire regulations).

Speed symbol

The speed symbol refers to the maximum speed capability of a tire. It is only valid for a tire that is properly inflated and loaded within the limits of the assigned load index.