http://www.blurtit.com/q988089.html
taking this as fact (scary on the internet)
Say it takes you 1 minutes to pump up your tire. Then you breath out 0.08 liters of CO2 in that time. 1 mol of gas at STP is 22.4L, so we're assuming 0.0035 mol of CO2. Molar mass is 12+32 = 44 g/mol of CO2 (roughly).

This gives us 0.154 g of CO2 pumping a tire. Now, lets assume you have an inefficient pump and you're breathing hard, It may take twice as long and you could be breathing 5 times as hard. Still only 1.5 g of CO2. Standard cartridge is 16g.

also, mollusk wins.