turning radius... whats better higher number turning radius or lower number?

The lower the number (number = feet), the tighter the truck will turn. Which is better depends on the type of work you are doing. Longer wheelbase trucks (larger turning radius) usually ride much smoother than short wheelbase (tighter turning radius) trucks.

 

think of it this way a tire the inside is a shorter distance tighter radius the outside is a longer distance longer radius

 

go out and look at a tire I am sure you will figure it out.

 

Imagine you're in your small car and you can routinely make a U-turn in a street without hitting the curb. You get in a another car that is either longer and/or doesn't turn as "tight" ... you try the same u-turn from the same spot, and HIT the curb.

In trucking and backing, a "quicker" turn can make a difficult back seem relatively easy as opposed to having to back it with truck with a longer wheel base (slower to turn)

Mostly the turn radius is affected by the wheel base (truck length) (center of steer axle to center of drive tandems), but the engineering of the steering system(s) also affects this number.

 

This is a basic idea of what a "wheel base" is. On a truck though, you measure to the center of the two axles at the rear.