I brought my MTB into reputable local bike shop to swap out a worn 5 year old tire. Front and back had 2.2" tires that were actually 2.2" wide. Mechanic says he has a new tire of the same kind ("Continental 29 Mountain King 2.2") in stock. I was thinking to go wider but say ok and ask them to install. New tire says "2.2" on the side, but installed and inflated it is 1.8" wide and visibly narrower than front.

Are tires sized like lumber, you take 0.5" off from nominal?

It otherwise seems fine, aggressive tread, etc. Should I care? Am I over thinking this? I'm just a fitness XC rider on single track trails in all kinds of weather.

  • 3
    I am sure this has been asked before, cannot find it - MTB tire widths are very 'nominal' - one manufacturers 2.0 and be wider than another 2.1. It probably varies between models from than manufacturer.
    – mattnz
    Feb 7, 2019 at 3:50
  • 4
    Tire width also depends on your rim inner hook distance (ID). Feb 7, 2019 at 8:02
  • Another gotcha is what is being measured? The maximum width from sidewall to sidewall? Or from outermost edge of lug to opposing lug? No, tyre sizing is nothing like finished timber.
    – Criggie
    Feb 7, 2019 at 10:24
  • I have a pair of tires that reads 622-32 but, when installed on a rim, measures 28 mm in width. Another pair of tires (different vendor) marked 622-28 and installed on the same rim measures 30 mm. So a nominally wider tire measures to narrower actual value. Both are slicks. Feb 7, 2019 at 11:34

1 Answer 1


MTB tyre sizes are very variable, and the only way to be sure what size you will end up with is to read online reviews and/or see it mounted on a wheel in person.

mattnz is indeed correct in his comment that size can even vary between models from the same manufacturer.

The Conti Mountain King 2(and the XKing that shares the same carcass) in 2.2" flavour are well known to come up small and are generally considered to be a 2.0/2.1. No need to be concerned though, as they are generally well thought of as XC tyres.

With these two tyres i'd be more concerned about getting the correct rubber variant of rubber compound (either the PureGrip or BlackChilli) than the true size of the tyre.

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