Thorn Resist Tube, 29" x 2.10", Presta 32mm, Sunlite Bicycles 29"x2.10", Thorm Resistant Inner Tube Presta Valve, 32mm Thorn resistant tubes are 6 times thicker than a normal tube making it more difficult to get a flat. Maintain proper pressure for the health of your tire. Thorn resistant tubes will tend to slide inside the rim when air pressure isn't properly maintained. Inner tubes will naturally lose air over time. It's imperative you put a pump on it with a guage before each ride or no longer than every 7 days.