11screw50

I suspect you are right about the axle ratings, I know on 2011-2014, the 6-lug wheels are only rated for 2025lb. the crappy P-rated tires are rated for 2500+.

The HD axle is probably the same but with different hubs for the 7-lug wheels that are rated higher.

And of course, they have different spring packages based on everything else.

brulaz

In 2015, the 3 rear axle's are listed in the Source Book with
Ring gear Pitch diameter of 8.8, 9.75 and 9.75HD and
If I'm reading the table correctly, these same rear ends have the following Lubricant Capacities: 4 pints, 4 pints and 5.5 pints.

Only the 3.73 EL rear end has the 9.75HD ring gear with the 5.5 pint Lube Cap. That's the HD Payload option.

11screw50

The source book information frustrates me sometimes. 2011 and 2012 don't list any rear spring ratings above 3850, 2011 lists 4000 and 4800 axles separately but all the specs appear to be the same (2012 lists them as 4000/4800). Only reason I see for not just listing it as 4800 is the 7 lug vs 6 lug difference?

Looks like the wheel capacity is down on the 2015's...most of the non HD wheels are only rated 1825lb. Even the HD wheels are only rated 2100. And while they list the ring gear as 9.75 and 9.75HD, they don't even list the axle rating. I'm no pro at navigating the Ford parts website but I can't find a ring/pinion noted as HD (they do however list the differential separately under base payload and HD but while the parts blowup lists the differentials separately, there is only one listing for each ratio ring/pinion.

brulaz

The rear GAWR is still listed as 4800# for the 2015 HD Payload trucks with 18" wheels in the Source Book. But as you point out, with HD 18" wheels only rated for 4200# per axle, I don't see how that can be achieved.

KR Kodi

iTrader: (1)

I believe that's for the max tow package. I know that's the rating ive seen in the 2015 Towing Guide.

However, all the new 2015 models at my dealer only are the standard tow package, and the sticker on the hitch says 11,000 lb max trailer weight and 1110 lbs max tongue weight.

So....if anybody that wants to tow heavy needs that extra 100 lbs of hitch rating, so definitely go for the max tow option.
.

nihilus

Perhaps this is why GVWR is 7850 lbs and not 8200 lbs. The wheels are rated at 4200 lbs which would be the bottle neck before the 4800 lb axles. Curb weight is about 2100 lbs for the rear of the 157"/163" trucks. That leaves 2100 lbs payload for the back. Since 100% of payload is never on the back, most trucks could still handle at least 2700 lbs when properly loaded. The 164" 2x4 might be overloaded on the wheels before the GVWR is reached, but I am sure they have wiggle room.
This is why the 17" HD trucks only have 7600 lb GVWR and around 2500 lbs payload. They are only rated for 4000 lbs, which leaves about 1900 lbs for the back. Again, payload is never 100% on the rear.
I am sure most are happy to take the 350 lb hit in payload for the HD trucks just so they don't have to deal with the 7-lug wheels. They are getting the same payload if not more than the last truck with the newer lighter truck. (It would be pretty foolish to get the 17" wheels on the HD truck though)

brulaz

Not sure about all that, and you could be right.

But just concentrating on the rear GAWR.

I've never seen a truck or trailer where the wheels and tires have less weight rating than the official rear GAWR. The rear GAWR posted on the door sill. That is supposed to be the official max loading you can put on that axle+suspension+wheels+tires. It is not the axle manufacturer's axle rating, it is not the spring rating, nor the wheel or tire ratings. It's all of them together and presumably is determined by the weakest link. And it looks to me like the weakest link here is the 18" HD wheels, and the rear GAWR should be 4202#, not 4800#.

That's a big (600#) drop, and I would rather have the 7 lug wheels and 4800# rear GAWR.

Really am curious what the actual rear GAWR on HD Payload F150s will be. If they are actually 4800#, I would like some one to explain to me how that is possible with those wheels.

EDIT: and Ford is listing 2500# as Max possible Payload, not 2100# for these trucks. Many (me included) will be disappointed to find the wheels can't handle the weight. Seems really stupid to me too. Why not use a higher rated 6 lug wheel? They exist. Some big trucks have only six lugs.