bakerlaw67 said:
Until I get a better idea of what I MUST do, based on facts and measurements, rather than speculation and 2nd hand info, I'm going to hold off on the suspension.
Unfortunately all you will get is speculation about your specific case, as there are just to many variables. What works on one rig may not work on another.
Here are the variables you are dealing with:
1973-1980 have different wheelwells than 1981+. So any experiences people have fitting your tires on the early vintage isn't going to be exact.
There were two different leaf spring setups on the '81+ K5's: 2 or 3 leaf front, and 5 or 6 leaf rear.
Springs sag, how much depends. Engines available for your truck were the 305, 350, 6.2 diesel, and maybe a straight six. AC or non, HD cooling or no, ALL add different weights on the front of the vehicle, when coupled with springs from another application that may or may not contribute to tire clearance.
I don't know what stock backspacing is, (another variable with non-stock wheels) but stock 15" wheel widths ran between 7"(?) and 8".
How about actual tire height and width, as opposed to stated? All manufacturers vary in how to close to stated size their tires run. Yours?
Anyways, that's not to be an ass, just show you WHY no one will give you a concrete answer.
I can tell you that I had 32x11.5R15's on my 1983 K5 with stock wheels, 305 and AC, non HD cooling, 2 leaf fronts, and it never rubbed.
As a matter of fact, just found someone that rubbed with 32" tires, so go figure.
Took me awhile to find it, but here is one thing that is a factor. Offsetting the wheel in the well is going to change where contact MIGHT occur, thus potential problems:
"FWIW, a 33x10.5" tire turned 45* (actually, it's quite a bit less than 45*, since the tire is not a square...just picture the tire as a rectangle, as you would see it if you were directly above it as it is installed) from straight ahead it's 33", while turning it is 34.6", while a 12.5" wide 33" tire is actually 35.3". Hence why more problems with 12.5" wide tires than 10.5" tires, and when turning/hitting bumps."
I
n other words, a tire appears as "larger diameter" when measured outside front edge to inside rear edge, which is what happens when you turn, and causes issues as tires approach the opening of the wheelwell. Fitment issues in this range of tire sizes is always with the rear fender lip. As you add diameter OR width (or change backspacing with wheels) to a tire, you change the "seen" diameter as you turn.
Go back to stock 15x8 wheels, and I'd give you a 90% chance that you won't rub. You can always do the spring swap, and see what happens, just plan on wheels if it doesn't work. (then hope that the 10% chance above doesn't bite you

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