Take the 2-minute tour ×  I have a mountain bike looking frame
with wheels that currently have road tyres. The bike is
classified as a hybrid.  My tyres state: 28" x 1.6 (42-622)
The rim: ETRTO 622 x 18  I am having difficulty locating any
mountain bike tyres for size 28". Can I use size 29"? Would I
need a different set of rims? Also, do I need a different tube
for these tyres?  My goal is to do some dry trail mountain
biking.  Lots of question. Thank you  share|improve this
question Schwalbe has some good info about tyre sizes and also
about dimensions. One other thing to watch out for is frame and
chain clearance. If your current tyres work fine (42-622 ETRTO),
then be careful about going wider than 42. A 50-622 tyre may not
clear the frame and chain even if it goes ok on the rim. Check
how much clearance you have with your current tires, both in
diameter and width before going wider. Being a hybrid it is
probably not designed for very wide tyres. –  Jason S Oct 27 '11
at 1:45 Great info, thanks –  Valam