Originally Posted by
Rayw83
My friend has some 25mm that he's offering to just give me, would that work?
You'll likely be able to make it fit.
Be aware that tires that are too narrow for a rim have to stretch out for their bead to dig into the rim's hook. This can make it harder for tires to take on an appropriate shape, and it can make them more prone to catastrophically rolling off the wheel.
Just wanted to see if it makes a difference going narrower like most road bikes.
Keep in mind that much of what you'll be testing is tire styles. Narrow tires tend to weigh less, so they do make for livelier acceleration. Other than that, effects of width are hard to separate from tire style and pressure. For instance, if your 35mm tires have any tread designed to dig at the surface, that'll be a significant rolling resistance disadvantage compared with road slicks. Suppleness is also significant; any GP4000S in any width will likely roll better than any Thickslick in any width, even though they're both road slicks.