18" 32-355, 18 x 1 1/4 40-355, 18 x 1.50 47-355, 18 x 1.75 32-357, 17 x 1 1/4 37-390, 18 x 1 3/8 47-400, 18 x 1.9 CONTINENTAL Compact 18" It's highly elastic, under enormous pressure, and can hold its breath: The inner tube. You can't cycle without it. The measurements are on the side of most tires. The first two digits indicate the width of the tire, and the following digits provide information about the tire. The Compact 18" is the right inner tube for numerous widths of 17" and 18" tires. Important, depending on rim height and pumps: The Blitz valve is 26 mm long. Width inch 1 1/4 , 1 3/8 , 1.50 , 1.75 , 1.90 ETRTO 32-355 , 32-357 , 37-390 , 40-355 , 47-355 , 47-400 Main color black Valve type blitz (DV) Article type/kind Valve length 26.0 mm Wheel size 17 " , 18 "