Portland Design Works' 38g CO2 cartridge is made specifically for high volume fat or plus bike tires. To give you an idea of the capacity, it will fill a a 26 x 4.8in tire to 6 - 7psi or a 29 x 3.0in tire to 20 - 22psi. It's designed to work with the Fatty Object CO2 Inflator, and is clean enough on the inside to be rated at food-grade, meaning it won't clog up your inflator or valve stems.
High-capacity CO2 cartridge for fat or plus tires
Designed to pair with the Fatty Object CO2 Inflator
Fills a 26 x 4.8in tire to 6 - 7 psi
Fills a 29 x 3.0in tire to 20 - 22 psi
Clean on the inside as to not clog inflator or valves