The aircraft is much heavier on takeoff than on landing. Fuel.
Yes, this.
Also consider that the tires can heat up during taxiing due to heat transferred from brakes to wheels to tires. Takeoff roll adds more heat to the tires as the heavy aircraft gains speed.
Then consider that at the point of rotation, the horizontal stabilator pushes down on the tail with considerable force, and the wings are not yet fully flying, meaning that the (now very hot) main tires are bearing a whole lotta mass. (Almost as if they are pushing the aircraft into the air.)
Imagine pushing down on one end of a teeter totter with a person of generous mass on the other (Selecting a name at random, say "Hillary".) The center of the plank will bear a lot of load stress as Hillary's mass is somehow lifted upward.