Young & Hungry,

Bro, hand width on the Tire Flip depends on the bodytype, IMO.
I'm only 5' 8" tall, but I can't flip a tire with a wide grip like a guy over 6' tall. I got short arms, and I can't get enough height on a wide grip for my hand transition. I usually take a grip halfway b/w a power clean grip & snatch grip.

I really don't like when people try to tire flip with their hands narrower than shoulder width. This puts too much strain on the biceps. You don't want to risk a possible tear.

Remember too, a big tire doesn't mean its heavier than a skinnier tire.
A skinny tire can be a radial, with more plys. Lots of plys mean alot of steel fibers in the sidewall of the tire.

Great questions bro! Keep 'em coming!
HIGA MONSTER.