20x4.0 Heavy Duty fat tire inner tube for all 20x3.8 20x4.0 20 x 4 1/4 20x4.2 20x4.3 20x4.4 20x4.5 fat tires. Upgrade your fat bike experience with these heavy-duty 20x4.0 bike tubes, designed for 20" fat bikes with tire sizes ranging from 20x4.0 to 20x4.5.
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