Few years ago, I got a men's Infinity Boss Three hybrid bicycle from Costco. It comes with 700c tires. I would like to replace them with mountain bike wheels, inner tubes and tires for more comfortable ride quality on paved bike trails.

My question is that what size of wheels, inner tubes and tires will fit on them? I don't plan to replace the drivetrain and brake components.

I realize the 700c tire's diameter is 27.56". Looks like I can just get a pair of 27.5" mountain bike tires?


2 Answers 2


Sorry - no. Presuming your bike matches the photos found on-line, your bike looks like this:

From https://costcofan.com/wp-content/uploads/2021/02/Costco-Infinity-Boss-Three-Bike-Front-rotated.jpg
Found at https://costcofan.com/costco-infinity-boss-three-hybrid-bike/

This bike has rim brakes, and they will only ever suit one size of rim. You cannot change away from 700c wheels safely unless your bike has disk brakes, or if you can somehow re-work the rim brakes to function for you.

It will be more cost-effective to buy an additional bike that matches your requirements rather than try to adapt this entry-level bike to be something its not. You would probably spend more on new wheels than this bike cost new.

  • 1
    I would also add one point to this reply: technically, the rims could fit some 29" MTB tires (the limiting factor will be the inside width of the rim), but because the bike has rim brakes, you'll be limited in the max width of the tires you can fit (unless you are ready to deflate the tires each time you mount and unmount the wheel).
    – Rеnаud
    Commented Apr 12, 2022 at 6:47
  • 1
    It should still be possible to fit wider tyres. The bike probably came with ~35mm tyres and it should be possible to go to ~45mm which should improve comfort (when run at low pressure).
    – Michael
    Commented Apr 12, 2022 at 9:53
  • @Renaud Excellent points - you two can add that as an answer, because while not directly answering the posted question, it totally addresses the underlying idea of "more-comfortable tyres" and how to get them. Need clearance in Frame, Fork , and even brake arms.
    – Criggie
    Commented Apr 12, 2022 at 12:30
  • @Michael yup - same as in previous comment - that's a valid answer.
    – Criggie
    Commented Apr 12, 2022 at 12:30

Assuming the photo in Criggie’s answer is accurate:

These bicycles usually come with ~35mm tyre width. Depending on the fork, frame and brake clearance it should be possible to mount tyres with up to around 45mm width, especially when used without mudguards.

Upgrading to ~45mm tyres should improve comfort noticeably, assuming you lower the tyre pressure to make use of the additional tyre volume.

For tyre compatibility in general what matters is the bead seat diameter of the rims. It’s the same 622mm BSD for 700c, 28" and 29" MTB tyres. However for 27.5" tyres the BSD is 584mm, so you won’t be able to mount them on those rims. Changing to rims with a smaller diameter would be difficult or even impossible on this bike.

If you can find 29" MTB tyres with sufficiently narrow width (the ~45mm I mentioned above) you should be able to use them. But you’ll probably want a trekking/city bike tyre like the Schwalbe Marathon.

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