In you enjoy bicycling, then chances are you will have to deal with a flat tire sooner or later. In most cases, fixing a flat requires a new inner tube. Knowing what size of inner tube to purchase based on the measurements of your bike tire will help you avoid confusion, fix the flat properly, and be back on your bike as soon as possible.
Often, the specifications for inner tube size are printed directly onto the sidewall of a bike tire. Before taking the time to make your own measurements, look for these specifications. You will find the inner tube size written in a format similar to the following: 26" X 2.0". This means you need an inner tube with a diameter of 26 inches and a width of 2.0 inches.
If you cannot find the specifications elsewhere, take out your measuring tape. Measure the inner diameter and width of the bike tire that the inner tube will be used with and write these down. Common diameters include 20, 24, 26 and 29 inches, and common widths include 1.95, 2.0 and 2.25 inches. Your tire may be different from these.
Go to a bike shop, sporting goods store or anywhere else that sells inner tubes. Match the measurements you took to the measurements shown on the inner tube packaging. If you have any doubts, consult a sales person before making your purchase.
Be sure to take note of the type of valve your bike wheel requires. There are two types--shrader and presta.