I don't have exact weights, but there was a DRASTIC difference between the stock Pyos with 245/75R16 Michelin street tires, and either of the current sets I run (H2 wheels with 275/70R17 General ATx, and 20x9 Fuel Hostages with 305/50R20 Yokohama Parada Spec-X). I think it'd be easy to throw a back out if not being careful moving these tires around, whereas I could almost handle the Pyos with one hand. If I had to guess, I'd say the Pyos were ~50-60 pounds wheel + tire, and either of my current sets are 100+.
I don't think I can tell a difference driving, but I definitely can tell a difference in the fuel mileage. I log fuel mileage pretty religiously (hand calculated), and I lost a solid 0.5 mpg switching to the Yokohamas on 20x9s, and another 0.5 mpg on the all-terrains. 1 mpg doesn't sound like much, but that's over 5% at the rough average of ~18. There's other factors at play there (wind resistance from wider tire, increased rolling resistance, etc.), but I think an additional ~200 pounds of rotating mass doesn't help anything at all.
That said, I love the look of my truck with both sets of current wheels. Never been a fan of the Pyo looks, so I'm not too upset about it.
Oh, forgot to add. The Michelin tires I had on the Pyos were (I think) the LT2. The plain-jane road tread pattern ones (not the sorta all-terrain looking ones), and in load range E (10-ply); I'm not sure if they even make them anymore or if maybe they've been upgraded. They didn't have the dry road grip my Yokohamas do, and they didn't have the off-road / mud grip the General ATx's do, but holy smokes were they amazing everywhere else. Quiet as a feather, smooth as could be, fantastic in the rain, and almost unbelievable in the snow (though a really narrow tire + 7000 pound truck helps there, too). And as a bonus, I don't think you can wear the damn things out. They had like 75k miles when I sold them on CL, and still had a fair amount of life in them. Only down side is you're gonna pay for them....but, I think you usually get what you pay for.