Amazon.com : Ultraverse Bike Inner Tube for 18 X 1.75/1.95/2.10/2.125 inch Bicycle Tire Sizes with Schrader Valve - Rubber Tubes for Kids Mountain Bike, BMX, Cruiser, Foldable Bikes – Set of 2 : Sports & Outdoors
Amazon.com : Eastern Bikes Curb Monkey 20 x 2.4 Inch Tire, with or Without Tube, Silver or Yellow Logo. Comes with Tire Lever Tools (Silver Logo, 1 Pack with Tube) : Sports & Outdoors
Amazon.com : MAXXIS Grifter Tire - 20 x 2.1 Clincher Wire Black : Sports & Outdoors
Pack of 2 Maxxis Grifter Tire 29 x 2.5 Clincher Wire Black/Tan EXO | eBay