Eyes forward, dude; we're talking about width here. The diameter info you post is pretty well accurate, but not relevant to the question of which tire sizes are appropriate for which wheel width. As for your claim that the 205/70R14 is fine on a 4½" rim, well, I spot-checked some current tire size guides published by the tire makers (easy to find on the tire makers' sites or on tirerack.com ) and none of them seem to approve a 205/70R14 on a 4½" wide rim. But it's entirely possible they're talkin' out of their butts, and some schmoe who sold some kid a '75 Duster knows more/better than the people who make the tires, so the kid'll have to make up his own mind.
