Metric Sizing System
Because Europe primarily uses the metric system of measurement, the metric sizing system was developed. It is essentially a conversion of the Numeric system. Section widths are notated in millimeters instead of inches. Originally, tyres not identified with an aspect ratio were assumed to be 82-series. When 60- and 70 series tyres appeared, the aspect ratio was added to the nomenclature, similar to the P-Metric system.
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| ISO Metric Sizing System
The International Standards Organization (ISO) Metric system combines the Metric system with a service description. The service description provides the load index along with the speed rating symbol.
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Millimetric Sizing System
The Millimetric sizing system is similar to the Metric system except that the rim diameter is also represented in millimeters.
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| Light Truck Numeric System
Similar to the Numeric system for cars, it lists the section width in inches, construction type, rim diameter in inches, plus the light truck designation.
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Light Truck Metric Sizing System
Similar to the P-Metric system, except the P is replaced with the LT light truck designation. Also, LT-Metric and P-Metric tyres differ in construction.
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| Light Truck High Flotation System
The same as the Light Truck Numeric system with tyre diameter added to the front.
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High Flotation vs. LT-Metric vs. LT-Numeric
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