GVW Rating of my GMC

[LongBox]

According to the plate on the LH doorpost, my 60 GMC 910 has a GVW rating off 5000 lbs. It has, according to the SPID, Heavy duty front and rear springs, a front anti sway bar, and 700 x 15 truck tires on 15 by 5.5 rims. The rear end is a 12 bolt, and it has genuine factory drum brakes all round.

It seems that the truck without a load or passengers would weigh somewhere right around 4000 lbs. Put in two passengers, and a full tank of gas, and your are down to a load capacity of about 600 lbs. Doesn't seem right to me.

Anybody got any information, or even opinions on the capacity of the axles, and the tires, so that I can figure out how much weight this old truck could carry?

[Alex V.]

My '67 'Burb only says 5,000 lb. GVW on the door tag, too, and it has HD springs, overload springs, HD shocks, and front sway bar, and it weighs 4,500 lb. by itself, so there has to be some discrepency.

[kwmech]

How much you plan on hauling in a 1/2 ton on coil springs?

[Coley]

I went through this once myself and here were my findings.
A 'real heavy' 1/2 ton from 70-72' would have maxxed out at 5400 lbs...so not too much more.
Now, here is what I have found to the 'limiter' or 'weak link' in the GVW ratings from that era.
Simply put: the tires....
A 15" tire in 1969-72 was typically a bias ply tire and the most they could rate them for was around 1500 lbs each.
Now, that meant a total of 6000 lbs for the truck. Factor onto that a certain 'safety factor' (due to customer abuse/misuse), and that would have been typical of any manufacturer, and you find that you have compressed your capability down to something safely below 6000 lbs like 5000-5400 lbs....due, in my opinion, mostly to the tires.
Today a 15" truck belted/radial tire (T23575R15) would easily take about 2000-2200 lbs which would drastically change that load advantage on a half ton truck. (ie: pushes that load capacity to 8000 lbs+ for the tires alone)
If GM had access to todays tire technology I think you would have found a different rating on these trucks....not millions of pounds more but probably more in the 6000 lb category found on mid 70's truck...when belted/radials become available and widespread.
My take.
Coley

[LongBox]

Interesting bit about the tires. I took a good look in the GM Shop Manual, and the specs show:

Frt Axle: 2500 lbs
Rear Axle: 3500 lbs
HD frt Springs: (F60) 2700 lbs
HD Rear springs: (G50) 4000 lbs

IIRC, this means that without considering the tires (and the brakes!), my HD half ton should be able to carry 6000 pounds. (2500 + 3500)

Tomorrow, I'll go and see what the tire sidewalls have to say...

[kwmech]

Originally Posted by LongBox

IIRC, this means that without considering the tires (and the brakes!), my HD half ton should be able to carry 6000 pounds. (2500 + 3500)

Tomorrow, I'll go and see what the tire sidewalls have to say...

Including the weight of the truck.

Yeah, I should talk, my 68 GMC has a GVW of 7500. Truck weighs in at about 5800 IIRC. Anyways, I went over the scales at the scrap yard with the bed of the truck full and my weight was 8820

[LongBox]

Years ago, I had a 71 GMC C-1500, and it weighed 4300 lbs with a driver and half a tank of gas. The GVW on the door post was 5400, so in theory, I could put 1100 more pounds in the truck (passengers plus load in the bed). At the time, I also had a full-size Chevy Stn wagon, and it could carry just as much. In fact, the Stn wagon had a TH 400, and the truck only the TH 350, which I found odd.

I asked the question in this thread because the truck came with a small camper in the bed, and I have always thought that a half-ton truck and a camper was a bad mix, unless the camper was an ultralight pop up style. I plan to take the camper off, as soon as I find storage space for it.

[LongBox]

OK. I took a look at the tires, and they are indeed, truck tires. In fact, they are 8 Ply rated, so can run 65 lbs pressure. At that pressure, they can handle a little over 2000 pounds each, so based on that, the GVW of the truck, with those tires, and a properly distributed load, is 6000 pounds, not the 5000 on the door post plate.

But boy, are those tires ugly, or what? I'd change to 6 lug rally wheels preferably about 8 inches wide, in a heartbeat.

[BILT4ME]

The GVW stands for Gross Vehicle Weight, which INCLUDES the weight of the truck, NOT how much you can put in it.

Also, from a legal standpoint, the Police will look a the the GVW on the vehicle and if you have exceeded it, you MAY be at fault if you have exceeded it and caused an accident. I've never encountered it, but it CAN happen.

In our state, the minimum licensing for a pickup is 12,000 LB. Go figure.

I once placed 4400 LB in the bed of my truck (pallet of ceramic tile) and I'm lucky it didn't blow my tires and bend an axle. I didn;t go crazy with it, but I could definitely see the tops of the trees with the headlights! I had a hell of a time getting the pallet out because I placed it in with a forklift, but only had a pallet jack to get it out. The truck had a wood floor and the wood floor was not so good afterwards. The PSI of load of 4400 LB on a pallet jack was way over the rating the wood could take.

Not good planning on my part.

[Alex V.]

My BIL (maintenance guy at Lowe's) once watched a customer insist on loading two pallets of shingles into the bed of his '07+ 1/2 ton Silverado. After placing both pallets on the truck it wouldn't move - tires were jammed so far up into the fenderwells it was rubbing. After removing one of the pallets it would move, but sat lower due to permanently bent springs. :O

[Coley]

I had a '72 Chevy Cheyenne/Super heavy 1/2 ton (5400 lbs GVW) that I carried an 8' (o/head) camper with. (I'll try to find a few pics). This was the second 1/2 ton I had carried this camper with....the first was a 1970 GMC 1/2 ton.
Regardless, I wanted to ensure the ('72) truck had it under control so I made sure of the following:
-Upgraded to 31"/10.5" tires (higher load rating @ 2500#/each, higher ground clearance)
-Rebuilt the brake system...front to rear for maximum (new) stopping ability
-Added Bolt-on Overload springs onto the LEAF springs (optioned into that truck from the factory vs. the standard coils)....noting the spring option in there was already the heavy duty
-Rebuilt the 4 core radiator to ensure maximum cooling
-Added a very high quality transmission cooler.
-There were a few other miscellaneous upgrades that I did to it, that I can't quite recall but I wanted to be conservative in the way I approached this.

Anyways...after that, I felt better about taking the camper on the (1/2 ton) truck...but it was still a hefty load for it.
I took it over the scales once with the camper, me/wife, fully loaded for camping at 6100 lbs. Not legal by GVW plate....but I determined we were in relatively safe territory given the way the truck/suspension/brakes/tires had been upgraded.
I wouldn't condone anyone loading there truck up the way I did....because I don't know if all the other stuff has been done to the truck and if it is all up to scratch.
My two bits.
Coley