Its not the rim size so much as the actual diam of the tire. 235-86-16, 265-75-16, 265-70-17, 225-70-19.5 tires ALL have the same 31.5-31.7" diam to them. The rim has nothing to do with this per say. Altho a 265-75-16 would be smaller than a 265-75-17 by and inch or 1/2" in active radius which is the real key.
You may be able to go to a 17 or 18" wheel, still keep a 75 series tire, smaller in diam and change out the effective ratio per say.
As I was also trying to point out, you tire diam, gear ratio speed you drive may be the BEST option for how you drive overall! For me to be driving 65 is pointless, as the max speed limit where I drive is 60 mph. I need to drive some 75 miles south on I5, and 60 or so north to hit a spot without a trailer to go 70mph. With a trailer over 10K I am limited to 60 mph no matter where I drive on an interstate here in Wa st. So taller gears are useless! The rigs with 3.73 gears and DOD's in the tranny would never get used. So for me, 4.33s would be the better use of ALL of the tranny gears. But alas, not available.
This is why I do not follow the overall tow rating baloney! Its really HP to a degree that limits the how well you will tow per say. I have a 2000 c2500 with a 350. It tows every bit as well or better than some BB 454's I have had int he past, but GM rates it lower than the BB V8's I replaced! Then again, the 350 has more hp, 20 lbs ft of torque less......so reality is, it can do as well or better being as it has the vortec option vs a 4bbl carb too!
Marty
