What is the weight of a 1991 Chevy Suburban?

The weight of a 1991 Chevy Suburban varies depending on the specific model (1/2 ton, 3/4 ton) and options. There's no single answer. You'll need to find the specific curb weight (weight of the vehicle without passengers or cargo) in the owner's manual for that particular Suburban. You might also find this information on sites specializing in vehicle specifications, though accuracy isn't always guaranteed.