km3 toyota rim

Tyre Sidewall

How to Read the Side of Your Tyre

ASPECT RATIO

The relationship of a tyre's sidewall height to its section width.

DOT MARKINGS

Each tyre requires Department of Transportation (DOT) number to be imprinted on at least one of its sidewalls; that number begins with the letters "DOT" and may contain up to 12 additional numbers and letters. The first and last digits are the most important:
The first two letters or numbers identify the tyre’s manufacturer and plant code.
Tyres produced after 1 January 2000, have a 4-digit date code at the end of the DOT number. The first 2 digits represent the week of production and the last 2 digits represent the last 2 digits of the year of production. So, 3500 indicates the tyre was produced in the 35th week of the year 2000.

LOAD-CARRYING CAPACITY

Indicates how much weight a tyre is certified to carry at maximum inflation pressure.

LOAD INDEX

An assigned number ranging from 0 to 279 that corresponds to the load-carrying capacity of a tyre.

OVERALL DIAMETER

The diameter of the inflated tyre, without any load.

OVERALL WIDTH

The distance between the outside of the two sidewalls, including lettering and designs.

SIZE

The combination of tyre width, construction type, aspect ratio, and rim size used in differentiating tyres.

SPEED RATING

This indicates the maximum safe speed at which a tyre is certified to travel under specified conditions. Speed ratings range from A (the lowest) to Y (the highest).

TYRE DESIGNATION

An alphanumeric code molded into the sidewall of the tyre that describes the tyre's size, including width, aspect ratio, rim diameter, load index, and speed rating. Most designations use the P-Metric system.

TYRE BRAND

This is the brand or manufacturer of your tyre.

TYRE PATTERN NAME

The tyre pattern name is the model or name designated to a particular tyre - this information is usually found after the manufacturer's name on the sidewall.

TYRE WEAR INDICATOR

Tread wear indicators ("wear bars") are located at the base of the main grooves and are equally spaced around the tyre. The tread wear indicators, which look like narrow strips of smooth rubber across the tread, will appear on the tyre when that point of wear is reached. When you see these wear bars, the tyre is worn out and it's time to replace the tyre.

TYRE TYPE

This designates the type of vehicle the tyre fits. P is for passenger metric. Other letters are LT (for light truck), T (for temporary spare) and ST (for special trailers). If your tyre has no letter, it signifies that your tyre is a euro "metric" size.

TYRE WIDTH

The width of your tyre from sidewall to sidewall. In this example the width of the tyre is 225mm.

TYRE ASPECT RATIO

This identifies the tyre's aspect ratio, which is the relationship of the tyre's sidewall height to the tyre's width. In this example, the sidewall height of the tyre is 55% of its width. The lower the ratio, the smaller the sidewall height, which means better cornering, but a rougher ride.

TYRE CONSTRUCTION

This is the tyre's internal construction, which is "radial." Almost every tyre on the road has radial construction, which means the cords of the carcass plies inside the tyre "radiate" directly across from one side of the tyre to the other. Other letters used are D, for diagonal construction, and B, for belted.

WHEEL DIAMETER

This number (in inches) indicates that the tyre is designed to fit on a wheel with a 18-inch diameter.

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