Originally Posted by Mountain_Owl
There's an old car/tire commercial whose tagline is 'Wider is better.' The tires on my bike are 26x1.95's. Would it be possible to put 26x2.15 tires on it, as one example?
Maybe.
The only way to know for sure is to try some. Sometimes bigger tires will fit the bike frame but the front derailleur will rub when it's in the granny position.
All tires of a given size won't fit the same either. Some have knobs that stick out on the sides that cause interference problems.