Goodyear 20" x 1.75-2.125" Heavy Duty Bike Tube, Tire Levers Included - Walmart.com
Amazon.com : 2 Pack 20" Bike Tubes 20x1.50/1.75" AV32mm Schrader Valve 20" Bicycle Tubes Compatible with 20 x 1.50 20 x 1.60 20 x 1.70 20 x 1.75 Bike Tire Tubes : Sports & Outdoors