The average truck consumer in the late 1990s wasn't like those of years before. At the dawn of computerized emissions controls, manufacturers were facing heavy financial pressure to push big trucks and SUVs as daily drivers; that meant new-generation trucks had to be more comfortable, more civilized, better looking and more versatile than ever before. That's a long list of requirements for any set of wheels, which is why GM kept so much about their design basics the same.
The 2011 Silverado wheel started with its bolt pattern: six lugs measuring 5.5 inches -- 139.7 mm -- from the center of one bolt hole to the center of the one across from it. Or, in wheel-maker terms, the Silverado had a "6x139.7" bolt pattern. It was set up for studs measuring 14 mm diameter and 1.5 inches tall. Depending on the specific model, it might have anything from 0 to 25 mm offset, but aftermarket wheels can use as much as 40 mm offset. The Silverado's wheel used a 78.3 mm centerbore, or center hole, and they came in a variety of wheel sizes from a small 15 by 7 inches to a massive 20 by 8 inches.
General Motors used this exact six-lug wheel for almost all of its full-sized trucks, going back at least as far as the 1988 model year, though it actually dates back as far as six-lug GM trucks produced in the 1967 model year. Some larger trucks, like the 2500-series trucks from 1988 to 2000, used wheels with a larger 100.7 mm center bore; half-ton S-10 and Blazers made from 1971 to 1991 used smaller 7/17 stud holes, and later-model half-tons used a slightly smaller 78.1 mm center bore. Outside of GM, this bolt pattern is incredibly common, widely used on six-lug trucks and SUVs from Nissan, Toyota, Mitsubishi, Jeep, Kia, Ford, Honda, Dodge and Isuzu, among others. Many of them used larger centerbores, which is no big deal in terms of interchange, since you can buy aluminum or plastic centerbore spacer rings. Offset ranges tended to be similar, too. However, many were drilled for smaller 12 mm or 7/16-inch studs, and drilling stud holes out to be larger isn't usually a good idea.
