Originally Posted by
pressed001
My road bike has 29mm wide tubeless-hookless rims with 28mm tires which pump out to 30mm on the wider rims. The benefits are lower pressure, more grip, and more ride comfort and are not limited to only road bikes. This is why manufacturers across the board are offering wider rims for all disciplines.
My latest 27.5" build uses Crest MkIII rims which are wider than their predecessor and I noticed a lot more grip while ascending. This is because the width of the tire's surface area increases dramatically with wider rims. That together with lower tire pressure means a lot more grip. (Honestly it would be great to understand the math behind it and calculate exactly how much more surface area. I guestimate up to 50% more lateral surface area.) I was even able to ascend some pretty heavy grades while out of the saddle, something that was impossible with my Stan's No-Tubes 355 rims (Crest MKIII pre-predecessors) and same tires (Thunder Burt).
Yes, this IS why rims are going wider.
However, there are limits to how wide you want to go with any given mtb tire.
The thing you need to keep in mind with MTB tires is that the treads are designed with a certain profile shape in mind. If you go TOO wide with the rim, you end up squaring off the tire enough that the side tread will be contacting the ground the whole time you’re riding, rather than just when you lean the bike.
If the tire you have pictured is a 2.2 on narrow rims, then you’re probably looking at a 2.0 maximum with a 30 mm rim. No 26” MTB 2.0 tire was ever designed to be run with anything close to that wide of a rim.
There are optimum rim widths for MTB tires, and it is a bit wider than we used to think it was. However, that does not simply mean that wider is always better.
Yes, 30mm is a fairly common MTB rim width these days. However, so are 2.4-2.6” tires for even non-plus sized bikes. Also, these tires are being designed for these wide rim widths.
If your plan was to run road slicks (or really any tire with no differentiates side knobs) on this bike, I don’t think this would be a problem. However, if you are looking at running mountain bike tires with any sort of side knob, I think you may end up being very disappointed with the results of a 30 mm rim and 2.0 (ish) MTB tire.