Tire and wheel size?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Jeremy Whitt

Junior Member
Joined
Nov 24, 2021
Posts
1
Reaction score
0
Location
Missouri
First Name
Jeremy
Truck Year
1980
Truck Model
GMC Sierra 2500
Engine Size
5.7 liter
Recently purchased a 1980 3/4 ton 4x4 GMC. It came with some later model 17 inch alloy wheels and the tires are toast. I think I want to go back with a 15 or 16 inch steel wheel and some mud tires. Anybody know the largest combination I can put on it? It is stock as far as suspension. Thanks in advance.
 

75gmck25

Full Access Member
Joined
Oct 13, 2016
Posts
2,018
Reaction score
1,811
Location
Northern Virginia
First Name
Bruce
Truck Year
1975
Truck Model
K25 Camper Special TH350 NP203
Engine Size
5.7
16” 8 bolt steel wheels of this vintage are easy to find, and there is a fairly good range of aftermarket wheels. The downside of OEM is that they are relatively narrow, so tires can’t be really wide. I’m not sure you would find 15” wheels that will work. Tires up to about 33” will fit with stock suspension.
 

mtbadbob

Full Access Member
Joined
May 9, 2021
Posts
617
Reaction score
921
Location
Montana
First Name
Bob
Truck Year
1987
Truck Model
V20
Engine Size
350
Recently purchased a 1980 3/4 ton 4x4 GMC. It came with some later model 17 inch alloy wheels and the tires are toast. I think I want to go back with a 15 or 16 inch steel wheel and some mud tires. Anybody know the largest combination I can put on it? It is stock as far as suspension. Thanks in advance.
These are 285/65/16's on my R20. I recently did a 2" Add-A-Leaf on the front only. I have 235/85/16's on my '89 2500 w/o any lift, also on the same GM Alloy's and they make it sit up nice & high. I guess it depends on if you want a fat tire or taller & narrower.
You must be registered for see images attach
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,124
Reaction score
6,038
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Recently purchased a 1980 3/4 ton 4x4 GMC. It came with some later model 17 inch alloy wheels and the tires are toast. I think I want to go back with a 15 or 16 inch steel wheel and some mud tires. Anybody know the largest combination I can put on it? It is stock as far as suspension. Thanks in advance.
POST YOUR RIDE
You must be registered for see images attach

we have a few guys with 1980 K25s here(and gal I guess I cant discount myself) but I lay claim to having the most benefitting of deceptively beneficial lighting and angle conditions in photos. And added on welded steel. And lack of original steel in far too many places esepcially ones where your feet may end up being lol.
Someone here had the square eye 1980 and that has always been so cool to see but whats your square like. Mines pretty simple in factory form and seen a lot. Is yours maybe one that is a little bit more presentable and driveable and thats why it had those wheels and tires?

You can buy 15 inch 8 lug wheels but you wont be able to find a tire that is 10 ply to put on. You can find 16 inch wheels with 10 ply tires. 10 ply is the tire construction that will be safely able to handle being loaded with weight, towing heavy things, etc. 6 ply places you where I wouldnt ever venture below since the load rating of each tire can probably cover your truck but then added load starts to exceed tire capacity. 8 ply is something you.. may? be able to find in a 15 but again it depends on what weight and what you would be trying to do with it. Load range isnt truly the amount of plys anymore, but Im using the word ply because a lot of people still know or understand things in the way of ply especially if using trailers because they still come bias ply often times but Load Range C D E is the 6, 8 , 10 equivalents for PSI and capacity ratings. There is an F range of 12 ply equals, but i dont encounter them much and I believe that starts to get into tires I perhaps wouldnt be able to find in 16 anyway. So, as far as your 3/4 ton 4x4 presumably long bed truck with stock heights and ambitions go, D and E load range tires. I just did a search and findiing a 15 inch tire for a truck in radial is not exactly easy if not just impossible now at load range D.

So I wouldnt go and do Load Range C unless youre going to be at max pressure and minmal loads applied to the tires from the bed or towing. A trailer that doesnt put a lot of force on the tongue like a dual axle with a balanced load and its own brakes would prob allow you to cheat over doing it without risk but that is unlikely your situation. I would get 16 inch wheels for sure to have the tire options and the load ratings you need. Now, if your truck is not going to be overdoing anything but you want the cheaper/better ride, D load range is probably your pick. If you want the capacity and strength to the cost of potentially tread life and ride, Load range E.

You must be registered for see images attach
You must be registered for see images attach

without having a pic closer on the tire I cant remember the size perfectly, but I believe 245 or 265 - 65 or 75 - 16 in this instance. My step dad had a 2005 Chevy 3/4 ton but on the HD end not the LD end and the size stock was either 235/75R16 · . 245/70R16
and I recall because it was HD his would be 245.. ok.. maybe Im not so certain. It to me remembers in my head as 245 but its maybe 265. I have a lot of numbers for this truck in my head because I had to look up tire sizes that would be the same height even if different size. So a 285 came into play but that was the now-spare in the bed.
You must be registered for see images attach

Of course this one just cuts off the size.. lol....
265-65-16 or 265-60-16 or 265 75 16 sound right.. We will just go with that. Truck is mostly stock height, tired springs but they were the HD front and back so its possibly slightly balanced but favors squat.
 

Rusty Nail

Full Access Member
Joined
Jan 29, 2015
Posts
9,735
Reaction score
9,534
Location
the other side of the internet
First Name
Rusty
Truck Year
1977
Truck Model
C20
Engine Size
350sbc
16s are prolly a better choice for a 3/4s 14 bolt rear than 15s.
I'm runnin 16x8s in 255/70s. (30x10)
You must be registered for see images attach
 
Last edited:

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
5,882
Reaction score
9,623
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
Since lots of stories but no answers…
Stock 16” wheels, biggest I’d go is 255-85-16 or 265-75-16 for full articulation with no rubbing.
You could stuff 285-75s or even 33-12.50s but they’ll be rubbin at full lock or some compression.
Don’t even consider 15s. Not a viable option.
 

Latest posts

Forum statistics

Threads
41,859
Posts
903,644
Members
33,372
Latest member
83elcowes
Top