I had a really nice post typed up with the math and links to sites where I got the information, but it was lost in a spell check/Internet burp. but the numbers I do still have is
Segway X2 golf, 120lbs
EZ-GO golf cart without batteries 550
Segway ground pressure alone 60lbs per wheel
EZ-GO ground pressure 137.5 per wheel
as the weight of the passenger increases the pressure of the Segway goes up as a function of half the riders weight, whereas on the EZ-GO its one fourth of the weight with the Segway matching the cart at 310lbs. However this is with the cart having no batteries and only one passenger.
I really wish my other post had survived,
Segway Golf Transporter
EZ-Go golf cart
BTW the gas version of the cart is in the 680lb area.
To cover another base, yes the size of the tire and the amount of compression affect the footprint of the tire and thus the ground pressure/ground loading, but the stats for the Segway weren't easily available.
Some quick researching goes a long way before posting sometimes, food for thought.