Ton rating
When light-duty trucks were first produced in the United States, they were rated by their payload capacity in tons (e.g., 1⁄2-, 3⁄4- and 1-ton). Over time, payload capacities for most domestic pickup trucks have increased while the ton titles have stayed the same. The now-imprecise ton rating is presently used to compare standard sizes, rather than actual capacities.
This has led to categorizing trucks similarly, even if their payload is different. Therefore, the Ford Ranger, Chevrolet S-10, and GMC S-15 are called quarter-tons (1⁄4-ton). The Ford F-150, Chevrolet 10, Chevrolet/GMC 1500, and Dodge 1500 are half-tons (1⁄2-ton). The Ford F-250, Chevrolet 20, Chevrolet/GMC 2500, and Dodge 2500 are three-quarter-tons (3⁄4-ton). Chevrolet/GMC's 3⁄4-ton suspension systems were further divided into light and heavy-duty, differentiated by 5-lug and 6 or 8-lug wheel hubs depending on year, respectively. The Ford F-350, Chevrolet 30, Chevrolet/GMC 3500, and Dodge 3500 are one tons (1-ton).
Similar schemes exist for vans and SUVs (e.g. a 1-ton Dodge Van or a 1⁄2-ton GMC Suburban), medium duty trucks (e.g. the Ford 1 1⁄2-ton F-450) and some military vehicles, like the ubiquitous deuce-and-a-half.