The climax of the episode "Accomplices" of the great The Spectacular Spider-Man cartoon, Rhino punches through several floors and pillars until he collapsesthis parking garage , and he holds up a significant amount of weight, and once the entire building goes down, he frees himself from all the rubble.
146 px = Car length = 4500 mm
Building width = 2085 px / 2 = Radius = 1042.5 / 146 = 7.14041096 x 4500 = 32.1318493 meters
Concrete thickness (based on the hole made by Rhino) = 23 px = 70.8904109 centimeters
Density of concrete = around 2,400 kilograms per cubic metre
Weight of one floor = 5518.48734 tonnes x 4 (since he holds four floors) = 22073.9494 tonnes (Class M)
He's potentially holding more than just these four floors, especially after the building collapses on top of him, but it'd still be Class M.