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Ever wonder how the width of your rim alters the width of your tire? Well, it’s time to get geeky.

We are partial to wide rims, and the favorite mountain bike tire of the shop is the Specialized Bicycles Purgatory. This knobby tire grips like a cheetah on our rocky trails and wider rims offer the strength we demand. We took super meticulous measurements of the Purgatory 29 x 2.3 tire on 3 different rims.The tires were all set to 25psi. Here is what we found:

  • External Rim Width 26mm and an internal width of 21mm yielded a width of 55.54mm and a height of 52mm.
  • External Rim Width 36mm and an internal width of 30mm yielded a width of 57.54mm and a height of 54mm.
  • External Rim Width 45mm and an internal width of 39mm yielded a width of 61.51mm and a height of 57mm.

Now you know and knowing is half the battle!



  • Tom Wheatley
    Posted August 7, 2018 at 1:20 pm

    At 25 psi, you need to factor in the weight of the rider as well as the possibility of bottoming out the tire / bending the rim on sudden shocks. As kids, we learned this by knowing what hills we could jump without breaking spokes. On the plus side, we learned how to repair them!

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How Rim Width Affects the Tire - The Bicycle Escape