segen77

When looking at the sticker on the door. it has a number for tire and loading information. Combined weight of cargo and occupants should never exceed "x"

Is this number limited by the type of tires you have, the suspension, or something else? I'm just curious how they get to that number and what aftermarket mods can increase it.

Thanks

Chazbo

+1

BCMIF150

I can't tell you how they come to the number, but can tell you that there is nothing you can do to increase the number.

11screw50

I suspect that a number is derived from tire limitations, axle limitations and suspension limitations, then they apply a modifier based on the engine and model of the truck before subtracting off all installed options.

This allows them to sell a 'max tow' package with essentially no changes to the axle, tires or suspension yet with a higher payload rating (essentially allowing them to 'push' certain things such as the EB).

Beyond that, I'm not certain that the sticker actually carries any legal weight (but I also don't advocate exceeding it because I do believe in large margins of safety).

And before anyone gripes about my thoughts, I do understand that the EB is better able to tow a higher weight than the 5.0 but this was a question about payload. If you'd like to point out the differences in tires, axle, suspension or chassis that justify the additional payload rating that comes with max tow, I'm listening.

Chazbo

Looking at sticker info for the tires and the axles, it appears that the limiter is the axles. My front Gross Axle Weight Rating (GAWR) is 3900 lb. My rear GAWR is 3850 lb. Adding these together is 7750 lb. My tires are rated at 2601 lb @ 44 psi. 2601 x 4 = 10,404 lb.

My GVWR is listed as 7300 lb. So it appears that I may have 450 lb of payload reserve lurking there before I reach the GAWR limitation. The added cargo weight will most likely be more on the rear axle than the front so the full 450 lb "hidden reserve" probably would exceed the rear axle GAWR.

Using the 7300 lb GVWR, the WAG axle loadings might be on the order of 3675 lb front, 3625 lb rear. 3850 lb rear GAWR - 3625 lb WAG @ GVWR = 225 lb "hidden reserve".

The other variable 11screw50 suggested was the suspension. This leads me to think adding some kind of suspension help (overloads, air shocks, etc.) might help level the truck when loaded, but the load would be limited to the GAWR limitation without other miracles.

Other relevant data:
2012 F-150 XLT, SCrew, 157" WB
Sticker Info:
1328 lb combined weight of cargo and occupants.
Axle - L9
Springs - VVAA

Presume Loading sticker was with full fuel included. 36 gal @ 6 lb/gal = 216 lb so with less fuel I might get more cargo?

Scaled empty weight of MY truck adjusted for empty fuel tank = 5950 lb

Aftermarket options : Bedrug, Truxedo LoPro QT Tonneau, WeatherTech Mats front/rear.

How I wish I would have got the HD suspension option. Anyone have the sticker ratings for a SCrew with the HD suspension option.

flixden

+1

I thought the max tow had different springs in the rear? Maybe I am mistaking here.
About the legality: yes, I am sure you won't get pulled over by a cop and get a ticket unless it looks very grossly over weight and dangerous.
But: if something bad should happen, and you end up in court, having been significantly over the manufacturers limits of your truck when it happened will not help your case, and could be difficult to explain at the best, and could be interpreted as negligence at the worst. Not worth trying IMO.

IronJoce

GVWR is a number the manufacturers come up with based on different things. Axels, springs, wheels, tires, cooling, transmission, differential, engine, etc. You have to make sure the weigh of you truck is not over GVWR and also making sure you're under each axel limit.

That being said, the tires are NOT the limiting factor in our case. Even the soft Pirellis are rated at 2400lbs each and without HD payload package, the maximum GVAR is 4050 with MaxTow. It doesn't mean they are good when loaded, it just mean they shouldn't blow up. If you plan on towing or carrying big load, get better (LT or at least XL) tires.

To get the payload on the sticker they take GVWR, subtracts 150lbs driver, about 8lbs per gallon for gaz and of course the weight of the truck.

About maxtow vs regular tow, some people seem to believe that if you have the 3.73 with regular tow you have the same exact truck as someone with max tow. Some other (like me) don't believe that and I think there is some differences.

In Canada, the sticker on the door has no legal value for a non commercial vehicle as long as this vehicle is registered. One could be towing a 15000lbs 5th wheel with a 2500lbs tongue weight behind a V6 F150, kill 5 people and get away with no legal problems. Stupid right??

For US it could be different, don't know.

smokeywren

Something else called the gross vehicle weight rating (GVWR). They subtract the shipping weight of an empty vehicle from the GVWR to derive that max payload number. But understand that is a MAX payload number available only when you have nothing in the truck but a skinny driver. For most owners that always have aftermarket options added and some tools and stuff in the truck, actual payload rating will be several hundred pounds less than the number on that sticker.

No, you cannot simply add GAWRs and get GVWR. There's a lot more involved in deriving the GVWR than the GAWRs. Frame, suspension components (not just springs), and brakes. IronJoce mentioned some of them, but omitted brakes. The brakes on your truck are designed to stop the vehicle under extreme conditions when the vehicle is not overloaded over the GVWR. Of course there is an unpublished safety factor in any engineered number. But anyone that uses that safety factor as a reason to overload their vehicle was standing behind the door when they passed out the brains.

Chazbo

Great answers IronJoece and smokeywren. I agree entirely. I was just noting that the axles and tires were not the limiter or the GVWR would be higher. If I were to fudge the payload to get my wifes garden stuff home from the store or nursery (topsoil, bark, landscape blocks, etc), I would not fudge it beyond the axle rating before my threshold of bad consequences pegged my worry needle, though not without risk. I would think the amount they lightened my wallet would help reduce the load.

Turns out I only pick up maybe 250 lbs over GVWR before I reach the rear axle rating. Not much. However, by picking up a heavy load with a near empty fuel tank and making her walk home, I am good to go!

mlbrand

Good thread, I've been wondering this myself.

However, it does seem like a conflict that my GVWR minus my base curb weight equals a bigger number than what the payload/tire sticker says.