Given the rapid arrival of 27. 5-inch wheels to the marketplace, the likelihood of your LBS or trail-side guardian angel not having the corresponding tube is pretty high at the moment. For this reason, we recommend grabbing fate by the horns and stocking up on the Q-Tubes 27. 5in Presta Mountain Tube. After all, it's better to be prepared then to be stranded. The Q-Tubes 27. 5in Presta Mountain Tube is available with a 32mm Presta valve and features a width of 1. 375 - 1. 75 inches.