I have a ZAC 79 front rim with a Deore HB-M530. I just found out I've got a flat tire (after thinking last week "Hmmm, probably I should get a new tire soon..." :D). I'm going to buy the Schwalbe Smart Sam Plus HS 476. However one thing struck me - I actually have one Smart Sam Plus on my rear wheel and it's of size 54-559 (26x2.1) while actually one the front I have one 54-559 (26x1.95) no-name tire that I've taken from a previous bicycle of mine. :D Both fit fine so I was wondering what the actual margin is when it comes to picking tires and whether I should by a 26x2.25 one for my rim. Speed gain (thinner tire better than fatter tire) is not such an issue here (I hope :D). I'm using my mountain bike on paved roads mostly though sometimes I also ride through woods (nothing too rocky) etc. and that's why I picked these tires.