Obtain the measurements for the tube. If you are carpeting a cardboard tube, the length and diameter of the tube are usually printed somewhere on the surface. If no measurements are provided, you can measure the length and diameter with measuring tape.
Measure the length end to end. Measure the diameter of the tube by wrapping a string around the tube. Use a pen to mark a point where the strings overlap and use a measuring tape to measure the distance between the two points.
Place a pad underneath the piece of carpet. Use an old piece of carpet or plywood.
Turn the carpet upside down and place it on the pad.
Mark the back of the carpet with the measurements using a pen and straight edge. Add an inch or two to the measurement to keep from cutting the carpet too short.
Cut the carpeting with a utility knife or carpet cutter using the markings as a guide. It's easiest to begin your cut approximately 2 inches from an edge, then cut toward both edges.
Wrap the carpeting around the tube. If the tube is large, get a helper to hold down the carpet.
Check the final fit and trim off excess carpet.
Unwrap the tube and apply carpet adhesive according to the manufacturer's instructions. Some require you to add the adhesive to the carpeting, while others require adding it to the surface.
Tack or staple the carpet in place with a carpet tacker or stapler.