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.

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    Possible duplicate of How are tire sizes measured?
    – ojs
    Oct 23, 2017 at 5:49
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  • Speed gain of a new tyre is more to do with the tread pattern and the rolling resistance than the width. If you only ride road, a smooth tyre is appropriate.
    – Criggie
    Oct 23, 2017 at 6:34
  • @Criggie I've I'm not mistaken 57-559 is not 35-622 or am I wrong? Oct 23, 2017 at 6:45
  • If you ride mainly on the road then why are you getting a knobby. Look at the bike and see how much room is left. I you can get you little finger in then it will probably take a 2.25.
    – paparazzo
    Oct 23, 2017 at 9:45

1 Answer 1


You've got some margin for tire width—at least 10 mm (although I don't know whether your current tires are at the narrow end or wide end of that range). It's also worth pointing out that the width printed on the tire can vary by a few mm from its actual width.

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    True. I also measured things a little bit. Plus I was able to find a slightly different tire (less knobby) from Schwalbe which measures 26x2.0. It fit like a glove. One day of using public transport almost drove me insane. Now I can enjoy my ride. :P Oct 23, 2017 at 19:12

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