I've said this before, and I'll say it again. Lightweight motorcycles use tires SMALLER than the 4" (100mm) behemoths on fat tire bikes.
The law of diminishing returns is LONG gone.
125cc motorcycles used to come with 2.75" tires on the front and 3" tires on the back as standard. When I fitted wider tires to my motorcycles I was still only using 3.5"(90mm) tires on the front and 4"(100mm) on the back only. Even large motorcycles used to only use 3.5" tires on the front and 4.5" tires on the back.
4" tires on bicycles is just a fashion thing and WAY beyond the limit of which size is useful for comfort.
Even a lot of brand new motorcycles with fat rear tires are still using front tires of no more than 4".
Last edited by AnthonyG; 06-28-21 at 08:14 PM.