8701.91 - Not exceeding 18 kW:

This HTS category, 8701.91, encompasses tractors classified under heading 8701 that are *not* of the type specified in heading 8709 (which typically covers industrial tractors for factory use). Specifically, this subcategory covers "other" tractors whose engine power does not exceed 18 kilowatts (kW). These are generally smaller, less powerful machines designed for a variety of tasks.

The primary distinguishing factor for this category is its defined engine power threshold. Tractors falling under 8701.91 will have an engine output strictly at or below 18 kW. This differentiates them from their sibling categories, 8701.92, 8701.93, 8701.94, and 8701.95, which cover tractors with progressively higher engine power outputs, starting from just above 18 kW up to exceeding 130 kW.

Within 8701.91, further subdivision occurs to refine classification based on the intended use of the tractor. The subcategories 8701.91.10.00 and 8701.91.50.00 exist to distinguish between tractors specifically designed and intended for agricultural applications and those intended for other purposes. This distinction is crucial for trade statistics and potentially for determining applicable duties or regulations.