How big should I go.

[HotWheelsBurban]

I think it was something to do with not wanting both sets of wheels rolling in the same tracks. In some weather and road conditions that could be dangerous.
For the expense, you'd think the engineering department had a good reason....

 

[8thNote]

I have a 1997 GMC 5 speed with a 305. Just got it repainted and both cab corners fixed. Still has factory wheels and was wanting to up grade a little. Thinking about going with 17x9 wheels and 265-65-17 . Is this a good combo or not?

This is strictly my opinion, but I'm convinced it's right:

Newer Rims in large, modern sizes look wrong on these old trucks. The period-correct rims/sizes always look better. The look "right". That being said, 15", 16", or 17" rims are the way to go on a gmt400

 

[fancyTBI]

I think it was something to do with not wanting both sets of wheels rolling in the same tracks. In some weather and road conditions that could be dangerous.
For the expense, you'd think the engineering department had a good reason....

I believe you are correct. Sometimes it is very noticeable depending on the wheel/tire set up. Other times it doesn’t look too bad.

 

[Pinger]

K model trucks do have a 2" narrower rear axle than their 2wd brethren.

I've had this argument here before....

That's interesting, I thought I had read that the Ks were the narrow ones. Guess I am misinformed....

..... and from every photo I've seen, Ks appear to have a narrower rear track than Cs. However, the consensus is that the 2WDs have the narrower rear track. I still trust my eyes on this one.

 

[Pinger]

. Thinking about going with 17x9 wheels and 265-65-17 . Is this a good combo or not?

That's the exact size I have on my C2500 Suburban. Works for me.

 

[Caman96]

I've had this argument here before....

..... and from every photo I've seen, Ks appear to have a narrower rear track than Cs. However, the consensus is that the 2WDs have the narrower rear track. I still trust my eyes on this one.

Everything I can find online says 2wd is narrower than 4wd. I get 67 1/2 measuring my K1500. Even a quick look on RockAuto shows 2wd axle length at 32”, while 4wd at 33”. That translates to 2” wider right there for 4wd.

 

[Bluey Chevy]

Previous owner of my truck put on some stock 18" rims from 2008 Silverado, I believe. It had 265/65 on it, which looked balloony to me.

I put on 255/70 which I like for looks and performance. Fills up the wheelwell without sticking out. I checked my Speedo against gps, and its accurate.

 

[OutlawDrifter]

In regards to the wider/narrower debate. In regards to the front track width vs rear track width, I think you'll find your 2" narrower debate.

Since the days of yore with GM 4WD's the rear track width has always been narrower.

 

[Caman96]

In regards to the wider/narrower debate. In regards to the front track width vs rear track width, I think you'll find your 2" narrower debate.

Since the days of yore with GM 4WD's the rear track width has always been narrower.

Why doesn’t someone one with a 2wd post their width to settle this or why are 2wd axles shorter or why is virtually everything online say 4wd is wider?
Edit: maybe misread, are you just saying the front to rear are different on 4WD? That I agree with.

 

[OutlawDrifter]

Why doesn’t someone one with a 2wd post their width to settle this or why are 2wd axles shorter or why is virtually everything online say 4wd is wider?
Edit: maybe misread, are you just saying the front to rear are different on 4WD? That I agree with.

Correct, the rear track width of GM 4WD's has been narrower since they started building factory 4WD's. I'm specifically speaking to the front vs rear track width on a 4WD.

I'm not getting into the 2WD vs. 4WD...honestly, I don't care about that...