2.3.

The snow grip index (SG) of a candidate tyre Tn shall be computed as follows:

SG(Tn)=f∙TPI/100

where
(a) f=1.000 when using SRTT14 as reference tyre per ASTM F1805-06, and
(b) f=0.987 when using SRTT16 as reference tyre per ASTM F1805-20,
and
TPI denotes the traction performance index as defined in ASTM F1805-06 or ASTM F1805-20, as applicable.

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