Originally Posted by
AOSTIRMOTOR
Fat tire and narrow tire have their own advantages and disadvantages, how should we choose? Here are some points for your reference.
Fat tire: The tire has large contact area with the ground, large friction force, strong grip on the ground, and stable riding on wet and slippery roads. But at the same time, because of its strong friction and heavy tires, it also consumes more electricity.
Narrow tires: Narrow tires are light in weight, less in friction and smaller in floor space, which saves more electricity than fat tires. However, the tread's contact area is small, and the grip is affected to some extent. When the road condition is bad or the slope and curvature are large, the riding will be unstable.
The above is the most basic difference between fat and narrow tires. If it were you, which one would you choose?
You've missed the most significant thing about wide vs narrow tires: you can use less pressure with wider tires, which, if coupled with a supple casing, adds a lot of riding comfort. Pneumatic tires were, after all, invented to provide suspension. A supple wide tire won't have any higher rolling resistance (you're calling it "friction," but really you're talking about casing hysterisis) than narrower, higher pressure tires but they will ride a lot more comfortably.
For my soon-to-be-built Alchemy eRonin I am choosing a wide, supple, fairly light weight tire: Rene Herse Switchback Hill 650Bx48 road (i.e., fine file) tread tires with the "Standard" casing. I've used the Herse tires in a number of sizes - 700Cx28, 700Cx32, 650Bx38, 650Bx42. Although they all have different names (typically named after passes in the Cascade Mountains) they're all the same tread. They come with a choice of casings: Extralight, Standard, and sometimes several varieties of heavier casing.
Tires like these are the closest thing to tubulars in a clincher format. They're light for their size, they are fast and they're very comfortable. They also provide great handling. They're not heavy duty utility tires, but the eRonin is a very light weight, sporty gravel bike not a commuter or a grocery delivery bike. It's actually no heavier than a typical traditional steel frame touring bike -- around 30 lb in a moderately large frame size -- and can be ridden with the motor switched off entirely. In fact, since it has the Fazua drive system you can actually remove the motor and the battery, replacing them with an empty cover, and ride it as a 22 lb carbon gravel bike.
I knew a rider who had a 2016 or 2017 vintage Trek e-bike, one of those 55 pound Class 3 flat-bar bikes, who used the 700C x 44 (I think) version of those same tires, also with the standard case, and was very happy with them. He said they transformed the ride of the bike. But he, too, was using the bike as a recreational bike for road rides, not as a commuter or utility bike.
Even though wide tires are typically far less flat-prone than narrow ones, I wouldn't use an expensive high-performance tire like the Rene Herse on an urban commuter or grocery delivery bike. You want to match up the cost and performance characteristics of your tires with the intended use. On a bike you use to get to work, long tread life and high flat resistance are a lot more important than a fast, supple ride since fun and comfort aren't your primary considerations.
But to circle back to your original proposition, if you have the choice, wider is better. The additional weight of a wide tire vs a narrow one isn't very relevant if you're talking about a bike whose weight is in the 40-60 pound range.