Forklift weight

The difference is dead Load vs live load. The floors adequate for the dead load. It’s spread out. It’s the concentrated rolling live load effect that loosens things up. Deflection vs. shear strength. A beam can deflect a lot, before breaking. My trailer got so bad, the 4 or 5 cross beams directly in front of the bogie flexed about 5”when being loaded, Had to install 4 new ones between them. Fixed the problem before the wood floor was destroyed. I’m currently trying to decide the best and easiest way to reinforce my 2x8 floor joists to support porcelain tile. The floor itself is strong enough to hold any amount of weight. I’m trying to minimize deflection, take the bounce out when walking, to avoid cracked grout, or tiles. The subject hits home today. Literally. Lol.