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Iso 5775





TIRES



Wired-edge tires


Wired-edge tires can be mounted on straight-side or crotchet-type rims. Such tires are designated with their ''nominal rim diameter'' and their ''nominal width'', separated by a hyphen (-). Both are measured in Millimeter s. A typical example of a tyre marking according to ISO 5775-1 is:

: 32-597 inflate to 400 kPa

  • The first number (nominal section width) is essentially the width of the inflated tire (minus any tread).


  • The second number (nominal rim diameter) is the inner diameter of the tire when it is mounted on the rim. The corresponding circumference can be measured with a suitably narrow tape inside the rim.


  • The recommended inflation pressure is marked in Kilopascal s.


The standard notes that the minimum inflation pressure recommended is 300 kPa for narrow tires (25 mm section width or less), 200 kPa for other sizes in normal highway service, and 150 kPa for off-the-road service.

The inner width of the rim on which the tire is mounted should be about 65% of the tire's nominal section width for tires smaller than 30 mm and 55% for those larger.

The section height of a tire is usually identical to its section width (for tires less than 28 mm, 2.5 mm have to be added to the width to get the height). The overall diameter of the tire is then the rim diameter plus twice the tire's section height. The ISO 5775-1 standard also defines procedures for measuring tires and for calculating from the marking the maximum dimensions of a tire, which are needed by designers to determine clearance distances to other bicycle components.

The standard defines a set of nominal section widths for wired-edge tires and lists recommended rim widths for each:

Older markings of wired-edge tires can be converted to ISO 5775 designations with the help of the following table: