"Capt. Geoffrey Thorpe" The Sea Hawk @See My Sig.com wrote

Wheels are 3"

I have found you need at least 6" wheels to be used on outdoor pavement,
with heavy loads.

I suggest air filled wheelbarrow wheels, 4 of them mounted on the sides of
two pieces of angle iron, with the bottom of the angles extended wide enough
for the wheel to sit on an inch or so off the ground.
--
Jim in NC