Just noticed looking at photos of the LiveWire that the tires are the same size as what I have on my Energica Eva. Which means from a physical size perspective the LiveWire is more like Energica instead of Zero. There is also the possibility the weight of the LiveWire is a lot closer to what an Energica weighs .
I don't think the cross-section of tires means much anymore. I have been seeing mid-size motorcycles that are now coming with what used to be sportbike size tires, 120/17 in front and 180/17 in the rear. My Royal Enfield seems quite happy with 3.25/19 and 3.50/19 tires, though. Personally, I think large rear tires are more of a styling statement than an engineering necessity.
But now that you mention it, I haven't seen any statement of the LiveWire's weight yet. Just looking at it, my guess is 550 pounds. However, H-D has never been too concerned about what their motorcycles weigh, so it could be even heavier.
