But why, exactly?
It sounds backwards in theory: One could justifiably assume a narrower rim and smaller tire would be lighter, more aerodynamic and therefore faster. But in actuality, new research and technologies have proved otherwise.
Without getting too lost in the data, here are five simple reasons why you should switch to wider rims and larger tires.
More Comfort1 of 6
Remember when you used to pump your 21-mm or 23-mm tires up to 120 PSI on your 17-mm-wide rims? The ride harshness is one you likely won't soon forget. But with wheel manufacturers like HED pushing rim widths from the then-avant garde 21mm to 25mm, issues with ride quality have been addressed head-on.
A standard 23mm tire mounted on a wide 25mm rim gives the tire more volume, which means there's more air between the road and your rim. With these, less PSI is needed to prevent pinch flats, and again, less PSI in your tire equates to a more comfortable, buttery ride experience.
Less Rolling Resistance2 of 6
Let's get this straight—rolling resistance is the amount of energy lost as your tire rolls over any type of terrain. It was once commonly thought that a higher PSI would allow you to glide over the tarmac most efficiently, but research has proved otherwise. Wider rims give you more air volume in your tires and therefore allow you to run a lower PSI. The tire can now absorb more of the chatter caused by rolling over imperfections, creating a smoother and more efficient ride. This is due to the flattened contact area with the road being wider and shorter with a wider rim—rather than longer and narrower like you'd see with a narrow rim.
Better Aerodynamics3 of 6
The old-school tire/wheel combination can be visualized as an ice cream cone, with the tire being the bulging scoop of ice cream and the narrow rim as the cone. On the other hand, the wider rim trend can be compared to more of a snow cone, with the rounder tire profile (ice shavings) flush with the edge of the rim (paper cone). This seamless transition makes for a more efficient aerodynamic profile—a.k.a. less drag and turbulence—in most headwinds and crosswinds. What do improved aerodynamics mean for you? Free speed and efficiency.
Better Handling4 of 6
Going back to the snow cone example, a wider rim gives you a "C" shape tire profile that promotes better handling and control. You'll feel the difference as you lean into a corner. There's less of a transition around the tire's profile, and you'll feel the extra grip from running a lower PSI (say it with us: more ground contact). If descending isn't really one of your strengths, a wider wheelset may just give you the little boost of confidence you've been missing.
More Versatility5 of 6
Many new bike brands include wider rims and tires as a standard option on new models. This is especially true on bikes equipped with disc brakes, where the absence of rim calipers grants the bike a larger tire clearance. Gravel rides are more popular than ever, so this added flexibility has fostered one-bike-fits-all solutions, with riders swapping out tires depending on the terrain and application. If you want to upgrade the bike you already have, be sure to check before you decide to invest—many older models won't have enough clearance for larger-volume tires or wider rims.