JBoesl and Deezul 1 are correct. In addition, the 5 degree bead seat angle on the 16. 5" wheel precludes the airing down of tires used on these wheels (in 4x4 low traction situations), that is unless having the tire dismount while running doesn't bother you. [these wheels were designed at a time when bias tires were used exclusively on the aforementioned wheels... the stiff sidewalls made the airing down of the tires a non issue anyway]
Also, the offset (i. e. , backspacing) of the 16. 5" wheels is incorrect for our Rams... they stick out too far to be properly (and legally in most locales) covered. In addition, they place more stress on wheel bearings.
However, if the above sounds good to you, by all means, let 'er rip!