Originally Posted by
DaveTG
Yes, wider tires will help adding better grip and comfort, but just the jump from 16" to 20", even with the same tire width, will improve the rolling on irregular surfaces, because the diameter increase helps to overcome some rough terrain easily. With a bigger diameter, it's like making the stones or the potholes smaller. If on top of that you have wider tires, you will add traction and comfort, but will add also some extra rotational weight.
This not my experience, Y had 3 wheelsets for my Birdy Titanium, one in ETRTO349 with 40x349 tires (Greenspeed Scorcher), one in ETRTO355 with 50x355 tires (SChwalbe Big Apple) and one in ETRTO406 with 32x406 tires (Continental Contact Urban, the Birdy frame doesn't accept tires wider than about35mm in ETRTO406).
The fastest was the 40x349 due to the very low rolling resistance of the Scorcher (these are high pressure, slick 40mm wide race tires), the most comfortable good on all type of roads, smooth or bad + trails and also fast the 50x355, the 32x406 wasn't as good as the two smaller and was less reactive.
Actually, the overall diameter with tires of 50x355 is about 455mm very close to the 470mm overall diameter of 32x406 (15mm difference = only about 3.19%).
Measurements show that with the same construction and same pressure, wider tires have a lower rolling resistance than narrow tires.