I never realized they weighed so much.
Before I went into the Marines at 18, many decades ago, I worked on a loading dock for a cargo transfer company.
I had to load the big semi trailer with all kinds of goods, including tires. Tires were easy since you laid them on their sides alternating in a zig zag pattern to minimize the room they take up............
if it was long enough ago you where probably loading bias ply tires, they used some sort of fiber belting to hold them together. Todays modern radials use steel belts, and I am sure that makes them heavier than a bias ply.
granted I don’t see many bias ply tires because they were phased out in the 70s for the most part, but the ones I have delt with did feel lighter if memory serves me right