1994 2500 Rims and Caps on a 1973 GMC C2500

[65Oldred]

Hi All,

I am looking at replacing the wheels on my '73 GMC C2500 project with a used set from a 1994 GMC 2500. The used set of wheels are steel with a beauty ring and a center cap with black lug nuts. I believe the black lugnuts are metric and the lug nuts on the '73 are USS/SAE.

Does someone sell a black lug nut in USS/SAE thread that will allow me to use these center caps (and wheels)?

I haven't tried to post a picture in a while. Here is a link to a vendor that seels a similar wheel (Chevy).

https://www.hubcaphaven.com/p/23207/...iABEgIOXPD_BwE

Here is my attempt to post a picture.

https://photos.google.com/search/_tr...u4_5GprSgfkpsr

[Willowrun]

I put the same rims albeit 4x4 rims from a ‘99 2500 Suburban on a ‘77 3/4 ton 4x4 truck. The lug nuts aren’t black, what you are seeing in your pic are plastic caps that screw onto the lug nuts and those caps screw onto external threads on the lug nuts and hold the center cap on. Too lazy to search but they sell conversion lug nuts that have the SAE internal thread to match your ‘73 wheel studs.

[65Oldred]

Originally Posted by Willowrun

I put the same rims albeit 4x4 rims from a ‘99 2500 Suburban on a ‘77 3/4 ton 4x4 truck. The lug nuts aren’t black, what you are seeing in your pic are plastic caps that screw onto the lug nuts and those caps screw onto external threads on the lug nuts and hold the center cap on. Too lazy to search but they sell conversion lug nuts that have the SAE internal thread to match your ‘73 wheel studs.

Thanks for the reply.

I found these on Amazon.

https://www.amazon.com/dp/B009SDA6YA..._6U2ZDbD3WWCY2

[hatzie]

The black lug nuts are actually plastic retainers that screw onto threads on the outside of the T400 lug nuts to hold on the center caps.
The T400 and squarebody 16" steel wheels have the same 8 lug 6.5" bolt circle as the 1968-1991 trucks.

You can use GMT800 wheels from the 99-2007 trucks and GMT900 wheels from the 2007-2009 trucks. GM changed to a metric bolt circle in 2010 or 2011 so I'd stay away from the 2010 wheels.

If you want late model aluminum wheels...
I have a set of PY0 aluminum wheels from a 2004 K2500 on my 2000 GMT400 C2500 and my winter wheels are from a 1986 K20.
I ran 17" N89 aluminum wheels from a 2005 K2500 on my 1976. They're on my 2005 K2500 now.
I've run Hummer III 17" 8 lug wheels on my 76, 86, & 2005. Didn't like em on my 2005.

The T400 lug nuts are 14mm metric but you can get 32 dual thread 9/16-18 SAE lug nuts on evilbay.
https://www.ebay.com/i/303331082942

[1976gmc20]

Isn't the back spacing totally different ????

I tried putting 6-hole GMT400 wheels on a square body suburban and they don't work at all even though the bolt pattern is the same

[hatzie]

6 lug wheels are a completely different group of parts.

IIRC the 8600 GVW and higher trucks of this era were actually a slightly different DOT class. Still a "light truck" but different as far as EPA and DOT compliance. This affected the wheels and suspension among other things.
Cats vs no cats, electronic carbs vs completely mechanical, wider and longer standardized springs, Hydroboost vs vacuum, ... the list goes on.

The 8 lug 16" GM wheels were close enough to the same animals to be bolt up replacements til they moved over to Metric bolt circles with the exception of the Hummer wheels.

The backspacing is not enough different to worry about if at all. I used steel wheels from a 2000 GMC on my 1976 and 1986 trucks. No rubbing and no projection past the fenders more than the nasty rusty stock wheels.

All of the big three use hub centric wheels IIRC and each has a slightly different hub diameter.
IIRC You could use 8 on 6.5 16" & 16.5" Dodge and Ford wheels on squarebody & T400 GM trucks with hub center ring adapters. You will run into trouble with the brake calipers hitting the center section when putting 80's Ford F-series wheels on a GMT400 and vice versa without a 1/2" spacer. Yes... I did this in the mid 1990's.

[1976gmc20]

Ok well how do the 2500/3500 IFS 4wd wheels work?

It appears (at least the 1500) that the hubs are mounted way outboard compared to the solid axle 4wds, apparently to leave more room for the CV axles to move up/down without binding - thus requiring the extreme backspace for the wheels.

[hatzie]

This thread is about 8-lug wheels on 8600GVW and heavier trucks.
Comparing the 1/2 ton and and lighter than 8600GVW trucks with 5 & 6 lug wheels to the 8600GVW and heavier light truck chassis with 8 lug wheels is comparing apples to oranges.

I've personally used 8 lug GMT400 C2500 steel wheels on a 1976 K20, 1979 K20, & 1986 K30. The difference was the lack of extreme rust and the gray rather than off-white color. The 8 lug GMT400 wheels don't have the retention bumps for dog dish caps either so you use a set of 32 9/16"-18tpi dual thread lugs to screw the plastic centre caps plastic retainers onto.

PY0 wheels from GMT800 2500HD IFS trucks through 2007ish. No offset problems on this squarebody. I have a set on a GMT400 2000 GMC C2500 Sierra classic with the same results as well.


H3 wheels on a squarebody. Note the slightly outward offset on these. The same problem is present on the H3 wheels that came on my 2005 GMT800 2500HD linked in my signature. They still look and work OK.

[1976gmc20]

Okay - just curious though … Do the HD 2500/3500 wheels just sit out farther on the IFS 4wd pickups? Or do those pickups somehow have narrower hub to hub width than the 1500's even though they are IFS ?

I reckon this means that the wheels off my 76 C-20 would fit right on a modern 8-lug pickup. Actually, I think the wheels from my 91 Suburban would fit on my 89 K1500, but not the other way around. The center holes would be way too big and the tire track would be about 8" wider but they should bolt right on (there would be no reason to do so).

[hatzie]

Originally Posted by 1976gmc20

Okay - just curious though … Do the HD 2500/3500 wheels just sit out farther on the IFS 4wd pickups? Or do those pickups somehow have narrower hub to hub width than the 1500's even though they are IFS ?

Just to make this clear these are 8600GVW and larger trucks with 8 lug wheels...
The 6.5" wide PY0 and steel wheels don't seem to sit any wider on the T400 or T800 trucks than the earlier rigs.
The 7.5" wide N89 wheels on my 2005 do sit slightly wider but not as noticeably as the H3 wheels.
The 8" wide H3 Hummer wheels do appear to stick out. You can see it in the picture I posted in this thread and on my GMT800 in my 2005 thread. Funny what 1/2" will do.
I think it has more to do with the actual width of the wheels than any difference in hub protrusion on the truck.

Originally Posted by 1976gmc20

I reckon this means that the wheels off my 76 C-20 would fit right on a modern 8-lug pickup.

Depends on what you mean by modern. GM changed to a Metric bolt circle around 2010 or so. Anything from an earlier GM with the 8 lug on 6.5" bolt circle should be fair game.

Originally Posted by 1976gmc20

Actually, I think the wheels from my 91 Suburban would fit on my 89 K1500, but not the other way around. The center holes would be way too big and the tire track would be about 8" wider but they should bolt right on (there would be no reason to do so).

GM uses hub-centric wheels meaning the wheels locate on the hubs not on the lug studs and nuts. This is why I mentioned the hub adapter rings for using some Dodge or Ford 8-lug wheels on GM trucks. It can be done but you need to take care when you start using parts from different manufacturers.
The wheel interchangeability is a lot more dicey on the smaller GVW trucks. More care has to be taken to make sure they'll fit properly. GM used several hub sizes and lug bolt circles on the 5 lug trucks and they played with the hub sizes on the 6 lug trucks.
You may get away with the larger hub holes on a 1/2 ton grocery getter without hub adapter rings but I wouldn't tow with it or heavily load the cargo space without hub adapter rings... Cornering hard might be a concern as well... just a plain old bad idea to do this without completing the job.

[1976gmc20]

Depends on what you mean by modern.

Oh, anything after 1987 or so

GM uses hub-centric wheels meaning the wheels locate on the hubs not on the lug studs and nuts. This is why I mentioned the hub adapter rings for using some Dodge or Ford 8-lug wheels on GM trucks. It can be done but you need to take care when you start using parts from different manufacturers.
The wheel interchangeability is a lot more dicey on the smaller GVW trucks. More care has to be taken to make sure they'll fit properly. GM used several hub sizes and lug bolt circles on the 5 lug trucks and they played with the hub sizes on the 6 lug trucks.
You may get away with the larger hub holes on a 1/2 ton grocery getter without hub adapter rings but I wouldn't tow with it or heavily load the cargo space without hub adapter rings... Cornering hard might be a concern as well... just a plain old bad idea to do this without completing the job.

Oh, I'm not going to do anything like that! For one thing, the last thing I would want on my pickup is damn 15" wheels. I was just saying that the old 6 lug wheels would bolt on and turn, but that the tire track would be way wider because half the wheel was sticking out because the backspace is about 4" different. The other way won't work because "new" wheels hit the tie rod ends on the front

I have five GMT400 6 lug steel wheels that I can't/won't use on anything because the center hole has been very nicely plasma cut to fit over locking hubs. One of them is serving as a self draining basket for tire chains, and another is currently filled with rocks and holding up a No Hunting sign. I have plans to use the others in a similar fashion to hold up t-posts that won't go in very far because of rocks

[KQQL IT]

I was bummed my caps from my 99 ccsb where too short for my 68. The dana 60 drive flange sticks out too far.
I thought the stock hub caps on my challengers would look cool.

[65Oldred]

Thanks everyone for responding with the great information. I decided to go old school. I painted the steel rims white and found a set of white 3/4 ton GMC hub caps in decent shape. Hmmmmmm. Should my bumpers be white?

Now I am on the hunt for two-tone passenger-side fender and a driver-side door. Something like this:

http://67-72chevytrucks.com/vboard/a...1&d=1113447162