Getting ready to replace the rear tire. Looking at going with the same: Maxxis MaxxCross IT - size 110/100-18 64M. Thinking about replacing tube although not sure yet. I've done a bit of searching and came up with the consensus that it is not necessary to replace the tube and/or rim band unless it is damaged. Correct me if I'm wrong there. So if I go with the tube replacement, what tube size is that (to clarify many of the websites list them as 4.00-18 or 4.50-18 which I believe is in inches and TR-4/TR-6, etc)? For some reason I find tube sizing confusing.