What is my max towing weight and gvwr?

I have a 1990 Chevy k2500 standard duty 4x4 ext cab long bed has a 6" suspension lift 3"rear blocks with add a leaf 3" and 315/75/16 tires. 14b SF, 350 Tbi, 700r4 both are brand new and the trans is built for 650hp. And has a non lockup converter and is internally locked in all gears. (Allows more cooling and lubrication) brand new regear to 4.56 ratio. New u joints/carrier bearing, exhaust is 3" single with shorty headers, k&n cold air intake, still installing hydroboost conversion, and air lift 5000 airbag kit. It has the trans cooler and oil cooler in the radiator and added a plate style external cooler to trans and engine oil. Also installed a trans temp guage.

I hope I'm not forgetting anything but I can't find anything on factory specs but I'm sure I could tow a good amount just don't know how much. Need max towing (camper) and max payload in bed. Thank you.

RPO codes will give you your GVWR. If they're not in the glove box anymore you can look them up on CompNine. $5, but totally worth it for the breakdown of all your options.

http://www.compnine.com/vid.php

(Think that's the third time I've recommended that someone do that today...)

Also should state in your door sticker.

With all the mods you've done to it, you can easily haul way more than what it was rated from the factory however if you get caught hauling way more than your truck is rated for from the factory then you'll run into some legal issues with the DMV and highway patrol.

Yeah but I figure they'll see 2500 on the the side of it and not look twice, hopefully lol

Your truck's RPO/door sticker will only list the GVWR, not your GCWR. GVWR is the XXXX - truck weight, passengers and cargo (including weight of a trailer on the hitch) but not the trailer's weight itself.

For instance, your 90 is a K2500, I can see it's 6-lug so it's the lighter duty truck. A 1990 K2500 Extended Cab 8' bed is rated for 7,200 GVWR, with a max payload of 2108. So, that 2108 should include the fuel, passengers, cargo and weight of the trailer hitch on the truck. Keep in mind the modifications you have done to the truck all should, technically, decrease this as they all add to the base weight of the truck. I cannot find the GCWR for a 90 truck.

Then you'll be factoring in a trailer (BTW the use of camper typically refers to the slide in pickup bed type), which will have it's own weight and a bunch of cargo you toss in it.

The payload ratings are pretty pitiful in my opinion, even on my dually almost any camper I haul is over.... both in payload and rear axle weight rating.... However even with it and trailer i'm still under my GCWR, even at 16,500 LBS combined.

BTW I see you are from WA, good to see more locals.

How is there nothing online about this. I find it hard to believe my tow rating not being very high, why would it be given a 2500 rating just on axle and spring upgrade. I just don't want to strain all my new stuff anyone have more info?

Andyvr4 said:

How is there nothing online about this. I find it hard to believe my tow rating not being very high, why would it be given a 2500 rating just on axle and spring upgrade. I just don't want to strain all my new stuff anyone have more info?

Click to expand...

Probably because your truck was made in 1990 before the internet was really a thing. I'm reading through the GM documentation from 1990 for the C/K truck and the information above was all it showed. Keep in mind that your K2500 is the 6-lug 14SF version, which in later years the 6-lug trucks with the 14SF were labeled as a 1500 and only rated to 6,800 LBS while the 8-lug 14SF trucks were labeled 2500 and were rated to 7,200 LBS just as yours is. 14FF trucks were rated at 8,600 LBS in 2500 form.

Here are the pages from 1990:



Your truck is 7,200 GVWR (Gross Vehicle Weight Rating). GVWR is the weight of the vehicle and everything on it. So the truck, you, fuel, gear in the bed, anything you've added (lift) and the tongue weight of the trailer you tow. The actual weight of the trailer is limited by your hitch, ball mount and the trucks actual GCWR (Gross Combined Weight Rating), which is not listed in 1990. GCWR is the actual weight of your truck, plus the trailer.

If we look at the 1998 trailering chart for a K2500 with 7,200 GVWR. You have 4.56 gears, with 35" tires, compared to a stock truck you are closest to a 3.73 gear ratio. A 350 powered K2500 4L60E auto truck with 3.73s can tow 6,000 LBS, and 750 LBS tongue weight.

Your GCWR is more of a function of the engine and gear ratio, since it's pulled weight. In your case, a 350 with 3.73 gears and an automatic can handle a GCWR of 12,000 LBS. Basically what this means, is your truck can be 7,200 LBS total, trailer can be 6,000 LBS total, but the combination cannot exceed 12,000 LBS. So if your truck was 6,000 LBS loaded and so was the trailer, you are golden.

Here is the page for trailering from 1998. This should be almost identical to a 1990, these trucks stayed largely the same.

Great info! I remember the days before Internet when you actually learned by trial and error. Lol

Am I not closer to a 4.10 then 3.73 ?