A nice trio of industrial Fordsons, probably headed for the docks in San Diego!
I don't know much about Fordson's. Where those rear tires/wheels common?
They are hard rubber bonded industrial tyres for use on concrete, much like today's forklifts use.
They were fairly common then, at least in industrial districts and for Road Commissions but as these tractors got replaced by forklifts or more modern tractors, if they weren't scrapped, they usually were outfitted with a set of steel wheels with cleats from an agricultural Fordson, or a set of Fordson spoked wheels fitted with rims to accept rubber tyres ("cut down" wheels).
Now a good set of these wheels are worth more than the tractor they are attached to.
And then WW2 bomber tires, talk about being stuck in the mud !