Ok.so Im not that far off..
Will I gain height with the 17's on.
Because i didn't measure the height of X before I put the winter 15's on.
Whats funny though is..when I brought the 15'home
I slid them up against the 17' which were obviously on the truck..and the height difference was or looked very minimal..I guessed the 70 and 65 of the sidewall profile would balance out..and therefore have teh SAME height in tires...
you know the plus 1 or minus 1 rule.

BUT then when I actually mountded the 15' and went right up to a SC with 17'..I put a piece of wood on top of both tires..and the slant downward towards the 15" was quite big..meaning the height of the 15" was dramatically less the 17"
I figure the pressure on the mounted tire would make that difference..
ok my head's spinning now