I was in the process of changing my MTB's tires to something more road oriented, what sizes could fit my rim? More precisely, how much thinner can I safely go?

  • 3
    Welcome to the site - this is probably the single most common question here, so rather than answering it over and over, check the linked duplicate and see how that applies to your bike. Upshot - depends on the inner width of your rims. If this post gets closed as a duplicate, please don't take it personally.
    – Criggie
    Commented Jan 11, 2023 at 10:19

2 Answers 2


The question as written is likely a duplicate. But here is some potential information.

First, you will benefit from knowing your rim's internal width, and if it is a hookless design or not. That should be marked somewhere on the rim, or on the manufacturer specs page for your bike. Keep in mind many department store bikes' specs won't have this information. I think that many current MTB rims on decent bikes are probably 30mm internal width. As a rule of thumb, I definitely wouldn't mount a tire whose nominal width is less than the rim's inner width. I think the guidelines in the link marked as duplicate (this one may be better) are conservative, and they do suggest that the minimum size should be something like 52mm (a bit over 2"). If you want to follow the guidelines, that rules out some performance road tires, e.g. the 30 or 32mm 650B Continental Grand Prix 5000 S TR.

If the rim is a hookless design, you may also need to worry about tire compatibility with hookless rims. The above Continental tire is compatible with hookless, but the model immediately preceding it is not compatible. This should be indicated in the tire manufacturer's literature. Keep in mind that you can run a tubeless tire with a tube inside, if you don't want to bother with sealant and the like.

You might also consider a slick or semi-slick tire designed for gravel bikes. For example, there are 47mm 650B tires by WTB and probably other manufacturers. Those may technically not conform to the requirements for a 30mm internal width, but they should be fine to mount. Those will be faster on pavement, and yet you'll still be fine going on many off-road surfaces.

Lastly, if you bought an MTB but you want something more road-oriented, that is an indicator that you may want to reconsider the type of bike you want. MTBs will never be as capable on the road as drop bar bikes. Further, you now have a suspension that isn't really helping you on the road - your tires provide more than enough suspension for that. Last, many drop bar bikes can handle many off-road surfaces - for that matter, many hardpack dirt roads can be traversed by road bikes, even older ones.

  • This would be worth posting on the linked question, if it is not already there.
    – Criggie
    Commented Jan 11, 2023 at 21:24
  • Thanks for your response. I'm still quiet now to cycling, specifically I own a B'Twin ST100.
    – Caesar
    Commented Jan 13, 2023 at 7:24

Without knowing rim specifics, impossible to answer. However, 32mm is a safe bet, unless your rims are very wide. You will never achieve a road bike performance even if you fit the best road rims and tires, and 28 - 32 mm is a sound choice for riders like you looking for more road oriented performance. Don't expect huge benefits unless you fit slicks. On a 26 rims, I was extremely happy with Michelin wild run'r, 26x1.1, which is 28mm. What's the model / make of your rims?

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