Hello all from the San Joaquin Valley California! It has been a while since I've messed with a Mtn Bike(16 yrs) and I'm kind of lost! Tire size- WTH is a 26x55/55? 55/599? Presta Valve- is it better than Shraeder? I only know about the difference because I was trying to exchange city for knobbies and I let out to much air before I realized the difference! Thanks for the help.