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Hey all!

I'm looking into the possibility of having my 1957 firetrucks papers adjusted to allow for a higher load. In the cab I have the original GM plate which states that the total weight of the vehicle is 8.4 tonnes, but when the car was registered they had this written down to just 6.3 tonnes. The original registration papers state that "Totalvikten nedsatt för att ej överskrida garanterat framaxeltryck (Total weight reduced in order to avoid exceeding the guaranteed front axle weight rating)". Seems odd to me that GM would state that the car is good for 8.4 tonnes of total weight if loading it up to the max means exceeding the front axle weight rating... Does anyone know what the axles on these things are rated for originally? Is there any way for me to get some sort of manufacturers proof of guaranteed weight ratings so that I can show this to my Swedish inspection agency and have them adjust the permissible max load?

Cheers!

The standard front axle rating was 4400 - 4500 lbs., there was an optional heavy duty axle available with a possible rating of 7000 lbs. Look up the GM Heritage Center and go to the Vehicle Information Kits, page down to the year and truck, then you can page through a lot of info on your particular model.

Wonderful, thank you so much! I think I found the correct document, as you say it does specify that the 2 ton trucks had a front axle rated at 4500lbs but since my truck is rated by GM to 18500lbs total weight I'm guessing it's a heavy duty truck and possibly equipped with the stronger axle... Gotta get down under the truck and see if I can identify what axle it has.

No such luck for me I'm afraid, measured the axle and it's only a 2.5 inches thick 4500lbs axle... Still don't get why the plate states 8.4 ton total weight if it's not possible to load that much without exceeding the axle rating...

Certainly the majority of the weight would have been on the rear axle, 8.5 U.S. tons is equal to 17,000 lbs, that is within the normal weight rating for the 2 ton trucks. I imagine that the rating for your truck is in metric tons, I did not research the conversion from metric to U.S. tons. My 2 ton truck is rated at 16,000 lbs GVWR with the standard 4500 lb. front axle. The rear axle on mine is a 15,000 lb unit, GM offered heavier rear axle options.

The 1957 Model 6502 (Flat Face Cowl) units here in the US had a min GVW of 14,000 and max of 19,000 pounds. To get to the 19,000 pound GVW rating you would have had to upgrade to 10-leaf front springs, 13-leaf main/6-Aux rear springs and power steering.

The 1957 Model 6502H would have a 21,000 pound GVW, with 12-leaf front springs, 7000 pound front axle, 14-leaf main/6-Aux springs, 16,000 pound rear axle, V8 engine and 9-1/2" Hydrovac.

So, your front axle is 4,500 pounds and the rear is 15,000 pounds for a total of 19,500 pounds. I don't know why they rated you truck at 18,500, but it does falls under the max rating of the axles.

Mike B

Thanks for your input guys! So the axle is correct and rated for 4500lbs, and yet the total weight on my truck is reduced despite GM specifying that it can handle the original total weight with this axle... I wonder if perhaps rather than load itself, it's got something to do with load placement? It is a fire truck after all, I believe it was at some point equipped with a water tank... Perhaps the tank is considered a fixed weight, and the placement of the tank meant the load rating on the front axle would be exceeded if the car was also loaded up with other stuff up to the original max rating? If that's the case, perhaps it is as simple as pointing at the makers plaque and ask them to adjust my papers as the water tank has been removed and the cargo weight can be positioned more freely and thus one should be able to haul more weight without exceeding the front axle rating...

If you study the specs on the GM heritage pages you will find that the GVWR will change with different size and ply of the tires. Maybe that is what was keeping the rating lesss than the spec plate states.

I don't know... I believe the original registration papers are required to state the reason for any modified weights, and since it specifically mentions that the reason is to avoid exceeding the axle rating I don't think it could be due to the tires...

Are you required to have a specific GVWR for your intended use?, is it going to be a commercial license/registration that will be inspected? If it is for your personal use and you already know what the axle ratings are then you can load it appropriately.

I was considering converting it to a flat bed or possibly ramp truck, and to be able to haul as heavy stuff as possible legally I need the correct weight in the papers. I'm not actually worried about exceeding the axle loads since GM themselves say it can take it, but as the numbers currently are I can only haul about 3800lbs of cargo and that's just not enough if I want to put some heavy machinery, cars etc on there... But no, it's not for commercial use. I just want to stay within legal boundaries. I should be able to carry more than double the current max cargo load according to the original plaque, but since the total weight has been reduced to to the axle load requirement the carrying capacity has been severely reduced...

I'm confused...your truck has a GVW of 8600 KG (almost 19,000 pounds) and you say it can only haul 3,800 pounds, that tells me your truck weighs 15,200 pounds empty. Is that right?

Here in the US the tire rating needs to meet or exceed the axle rating so the axle rating can be used to calculate your max load. In your case the front tires need to be rated at 2250 pounds each (4500# axle) and the rear tires need to be rated at 3750 pounds each (15000# axle) to be legal to max out at 19,000 pounds GVW. If you use a lower rated tire then the GVW gets lowered as well.

Mike B

Not quite, sorry if I've not explained properly. The truck is rated to almost 19000lbs according to the manufacturers plate in the cabin, but my registration documents state the total weight as only 14000lbs. And since the weight of the unloaded truck is specified as just over 10000lbs, I'm left with just under 4000lbs max legal load. The reason for the lower total weight is, according to the original registration papers, in order to avoid exceeding the max permissible front axle load. if it was due to the tires, I believe that's what the document would've said since I have seen similar documents stating that the total weight has been lowered due to load limitations on the tires. It doesn'tmake sense that they would attribute the lowered total weight to axle limitations if it were really about the tires...

I don't know your laws, so won't be any help in figuring out why someone in the past de-rated your truck. Here in the US many States allow the owners to lower their GVW classification/rating to reduce their annual registration fee's. If they get caught going over their reduced GVW rating they get a heavy fine.

I would think showing your data plate to the authorities would allow you to go back to the original GVW rating (8600 KG)...

Mike B

I'll have to ask the inspection agency and see what my options are. I'm guessing it's got to do with weight distribution, so maybe it's as easy as converting it into a flatbed truck and I'll have the correct weight back. I hope the plate is enough to convince them, but I have my doubts... They are a nitpicky bunch, might need some form of official GM document that says this exact truck is rated at 8600kg total weight...

If and when you remove the heavy steel firetruck rear section and the pumping equipment from the front, you will find a huge weight savings. My '57 2 ton with a cab high 15 foot wood grain box weighs 7400 lbs empty.

Oh yeah, that body probaby weighs a ton. Not only will that weighht reduction mean I can haul more load, but I believe it will also allow me to get the truck back to the original total weight rating as I'll be able to distribute the weight more freely along an open flat bed. Makes sense to me at least, as long as I don't exceed the weight rating on the rear axle I don't see why our inspection agency would have issues with re-rating it for its full capacity.