Glenn lucks out, heightwise in pictures, because his hair is "higher," giving the illusion he's a hair (ha!) taller. Tim goes for length going down, Glenn's goes up.
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I think it makes Glenn look a tad taller, when in fact I'm prety sure they're the same height. Shoe heels, too, play a part, too. Back in the 70s, I think Glenn depended on cowboy boot heels to add like 2-inches, but I don't think he can stand in those anymore for a 2-hour show. (Though the black/white shoes probably have lifts/heels in them somehow.)
I'd put them both at 5'9.