How long is the trailer on an 18 wheeler?

Anywhere from 20 to 53 feet. A 26-foot trailer is called a pup trailer, and on the freeway they're pulled as doubles. (Plus they only have one axle, not two.) There are a lot of 48-foot reefers floating around; this is what you'd use to pull food to a supermarket in a congested area because it's not as hard to turn as a 53-footer is. Guys who pull intermodal containers have four basic sizes: 20-foot, 40-foot, 45-foot and 53-foot, and a lot of flatbeds are 48 feet long. Most dry vans are 53-footers. In certain states like Texas, you may even see a 57-footer