Main problem with 16.5" is the lack of tire options. Some guys want the 16.5 rims so they can run relatively cheap tall bias ply military tires, but most of us want more normal sized radials, and for that the 16" rim offers far more options. The steel rims I believe are 7.5" wide and are meant to be mated with the 235/85R16 tires. I like these a lot. The aluminum rims I believe are a bit wider.
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD
STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering
BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2