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Greg G.

Techinical Bulletin--NSW vs Listed Size ST1-4/TT1-4 3-12-18

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Greg G.


NASA Section Width (NSW) versus Listed Tire Size in ST1-4/TT1-4 classing



6.5.2 Modification Factors

Tire Size: NASA Section Width 266mm or smaller (DOT-approved)

Or any currently produced size 245 or smaller = +0.6

NASA Section Width 267mm to 282mm (DOT- approved)

Or any currently produced size 275, 245 or smaller = +0.3

(Note: Deletion of the use of labeled tire size is probable within 6 months)


Clarification: If a DOT tire is compliant with the NSW section width tool, the Modification Factor applies, regardless of the tire size printed by the manufacturer on the tire.

(example: if a tire fits the 266mm measurement tool, but the tire is listed as a "275" by the manufacturer, the + 0.6 Modification Factor does apply).


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