What's the difference between the "wheel base" dimension and the overall width of the machine?
As I mentioned before, I am looking at fork trucks and taking their size/maneuverability into strong consideration, so I am very confused by a width measurement of 116 inches and then a wheel base measurement of 138 inches.

Edit: A few more questions:
Which tires are better for concrete; pneumatic or cushion tires? Which are better for asphalt (although I think most of the truck I'm looking at will sink straight through asphalt, especially in the summer).
What's the typical life expectancy of each tire? Or rather, which tends to last longer?