I use the tires that came on the bike to begin with, and put in slime from a bottle, along with mr. tuffy liner, on the rear tire. I have had to air up twice for some leaks, but it will hold for a little while, then I stop and refresh. I carry tools, but rarely am willing to fix a flat on the run. I usually get home and then fix at my leisure, but slime and liners have SIGNIFICANTLY reduced the number of flats. from 4 in 4 days to none in months...