no, you are wrong. Last number on the tire is the Metal Rim Diameter. First number is width, 2nd number is how tall is the rubber part.
If you are trying to make the tire bigger in Diameter, you go with 235/70/R16. If you want it wider, you go 245/65/R16. You can NOT mount a 17 inch tire on a 16 inch rim, it just doesn't fit physically. You have to buy the whole Wheel, not just the tire.
Sorry for being incomplete.
The existing tires are 235/65/16
i intend to change the rims to 17"
the most desirable tires are
235/65/17 annd from what i can tell they have a tip to tip outside diameter of 28.5"
from what i can tell the origonal tires are 27.5 tip to tip outside.
Visually it looks fine with the increase...
Could i "squeeze" another 1/2" out and go to 225/65/18