SRW Tires

[Dave_H_M]

I tow with an F250 and am always concerned/watch the weight capacity of the tires. I see the folks referring to the weight ratings of the F350.

What kind of tires/weight ratings do the SRW 350's have that helps boost the hauling capacity.

Seems like only E Rated are available for my F250 with 17" rims. thanx

[RoyJ]

Cummins12V98 wrote:

Not a good idea. You can get a D in a bigger size and carry more weight than an E but the D will be a very bouncy tire.

Les Schwab was famous for that switcharoo.

Remember though, even the letters are arbitrary - there are E tires that are rated 65 psi.

The actual ply construction are also all over the place. There's no guarantee a D "bounces" more than an E. I've had mud terrain Ds with much stiffer sidewall plys than highway Es.

[Cummins12V98]

valhalla360 wrote:

RobWNY wrote:
Putting sticker numbers, Spring packs, Timbrens, Air bags and what's considered legal weight aside for a minute, aren't the two real determining factors what a truck can handle the GAWR and the Max tire weight rating with the tires truly being the weak link because the axels can really handle more than their rating? Maybe I'm missing something but if I had the same E rated tires with weight ratings of 3,750 pounds on a 3/4 ton and a one ton truck, regardless of what was added to beef things up, isn't the max payload of both trucks 7,500 pounds? Isn't the tire ratings usually the weak link in max weight capability in heavy duty trucks?

Personally, I stopped looking at Letter Grade Ratings. It's an outdated system based on when they made stronger tires by adding more plys to the tire.

Look for Load Ratings that meet your needs.

But it's also the springs in many cases that are also a limiting factor. The axle itself is usually the same. The GAWR is the weakest link in the rear suspension, not necessarily the axle itself.

Not a good idea. You can get a D in a bigger size and carry more weight than an E but the D will be a very bouncy tire.

Les Schwab was famous for that switcharoo.

[Fstmvrerik]

Always check your rim capacity also. I bought a SRW F350, I checked the tire capacity of Nitto 20" tires, it is 3750lb each. The rims that came with the truck were rated at 2640lb. I did not know this until I had cracked a rim (weight or off road hazard).
I now have 4 k rims.

[JIMNLIN]

The Ford Super Duty brochure showed that the F-250 used a lighter capacity axle from 2011 through about 2015. There was a great debate online with most contending that the same axle is used in both the 250 and 350 SRW for mass production cost saving.

Ford tech guys over on FTE forums say the F250/F350 SRW 6.7 diesel gets the same rear axle with the larger diameter axle shafts.

They also say its the F250 gasser engine with much less torque get the smaller rear axle (smaller diameter axle shafts).

Make sense as axle shafts on the full floater rear ends has nothing to do with carrying weight. The axle shafts just twists the gears.
The two bearings in the axle tube ends carry the load.

[lenr]

My opinion--yours may vary. Most of below comes from knowledge of 2011 through 2016—recent years may have changed some of this, although I haven’t noticed much as I look at recent years documentation.

The Ford Super Duty brochure showed that the F-250 used a lighter capacity axle from 2011 through about 2015. There was a great debate online with most contending that the same axle is used in both the 250 and 350 SRW for mass production cost saving. It is possible that the lighter axle was used for 2011 Job 1 250s to use up existing supplies from 2010. However, everyone now believes that the axles are the same from at least 2012 and possibly 2011. The F-250 is typically derated to 9900 or 10,000 lb. GVWR even though it can physically handle more. This allows insurance and licensing cost savings in some states. The F-350 since 2011 adds the auxiliary spring and that’s about it other than labeling. So, yes, in agreement with most of above, tires are likely to be the limiting factor. I have noticed in recent years that the 20” tires can get as much as 14,400 GVWR.

[ksss]

I think 18's are really the way to go. Many tire options, you get more side wall height to protect the wheels if your off road at all. It is typically pretty easy to find a set of take off wheels at tire stores from guys that have put custom wheels on as Grit Dog stated.

[FishOnOne]

Grit dog wrote:

JIMNLIN wrote:
With todays 18" and 20" LT E in the 3800-4000 lb range tires the weak link is OEM wheels and OEM rear spring pack ratings.

F250's come with 17" or 18" and 20" wheels so moving up to LT E in a 20" wheel gains a lot of capacity over 17" sizes.

^This. 17s are not viable Heavy load LT tires anymore. Been that way for 5-10years now.
Get some takeoff 18s or 20s if you actually need them.
Or is this just a hypothetical question?

I agree go to ebay or craiglists and pick up some 18" tires to get a substantial improvement in tire capacity if it's required.

[Grit_dog]

Royf did a good job of regurgitating the payload specs.
But what he didn’t mention is that the only differences between a 250 and 350 srw apples to apples is a heavier duty rear axle and greater spring capacity.
Combined with the fact that some 3/4 tons are still set at 10klb gvw and even the 10.5 sterling axle in the 250s is rated for almost 10klbs, the physical differences are almost a moot point.
A fact that many cannot understand or refuse to believe.
So Dave just because you think you did something wrong by not specifying a gvw ? Package, it doesn’t matter. Only low end factor on your truck, presume it’s old or base model, is the 17s.

[Grit_dog]

JIMNLIN wrote:
With todays 18" and 20" LT E in the 3800-4000 lb range tires the weak link is OEM wheels and OEM rear spring pack ratings.

F250's come with 17" or 18" and 20" wheels so moving up to LT E in a 20" wheel gains a lot of capacity over 17" sizes.

^This. 17s are not viable Heavy load LT tires anymore. Been that way for 5-10years now.
Get some takeoff 18s or 20s if you actually need them.
Or is this just a hypothetical question?

[RobWNY]

Dave H M wrote:
Don't get me wrong, I am happier in a pig in you know what with the F250 over all.

Thanks again

Pigpen?

[Dave_H_M]

Dang, you folks provided all the skinny I was wondering about.

Duuuh, I failed to speck out the load rating/RAWR of the ole F250 CC short box when I ordered it. :S

Yeah and as stated, the 6.2 even with 4.30's does not spend the majority of its time in 6th when yanking the 10K fifth wheel from central IL to Myrtle Beach/Murrells Inlet SC. Don't get me wrong, I am happier in a pig in you know what with the F250 over all.

Thanks again

[RoyF]

From the 2020 Ford-heavy-duty brochure, there is a ovelap in payloads for the F250 and F350. (These figures may be slightly different for 2021.)

There are many GVWR choices: 9,900 up to 10,800 for the F250; 10,000 up to 12,400 for the SRW F350. Adding 4-wheel drive to either reduces the payload by 400 to 500 lbs. And, for some reason, adding a high-capacity towing package to the F250 reduces its payload.

With so many variables (GVWR, regular or crew cab, short or long bed) there is considerable overlap between the highest F250 and the lowest SRW F350 payloads.

For the crew-cab short-bed preferred by many RVers, the numbers for the F250 with tow package are 3,750 (4x2) or 3,320 lbs. (4x4).

For a comparable SWR F350, the numbers vary from 3,650 (4x2) or 3,220 (4x4) up to 4,460 depending on the choice of GVWR.

For a crew-cab long bed, the numbers for the F250 with tow package are 3,520 (4x2) or 3,040 (4x4).

For a comparable SWR F350, the numbers vary from 2,990 (4x4 with lowest GVWR) up to 4,730.

Bottom line: the SWR F350 payload for a given configuration is generally (but not always) about 500 lbs. greater than that of the F250. The payload depends highly on the configuration: GVWR, choice of engine, cab, and bed.

For maximum payload, the F250 short-bed, regular cab and no tow-package can have payload up to 4,260 lbs. (4x2) or 3,820 (4x4).

The SRW F350 short-bed, regular cab can have payload from 3,630 up to 4,960 lbs, depending on the choice of GVWR.

To make a choice between F250 or SRW F350, it seems that one should first decide about the cab, the bed, 4x2 or 4x4, and the engine. Next, we need the required payload: hitch weight, weight of fuel, other things in the bed and back seat. Add a few hundred pounds for good measure. Only then can you make a choice.

ps: my 2008 SRW F350 is showing signs of age (not with engine or transmission, but with various other things), so I am trading for a 2021 SWR F350: a special order to get exactly what I want, and hoping for delivery in February. That's why I have been looking so carefully at these numbers.

[BurbMan]

StirCrazy wrote:
when I bought mine to get the 11500 gvw package you had to get the 20" wheel option otherwise you could only get a 11000 gvw truck.

I have 12,300 GVWR with 18" factory wheels.

[valhalla360]

RobWNY wrote:
Putting sticker numbers, Spring packs, Timbrens, Air bags and what's considered legal weight aside for a minute, aren't the two real determining factors what a truck can handle the GAWR and the Max tire weight rating with the tires truly being the weak link because the axels can really handle more than their rating? Maybe I'm missing something but if I had the same E rated tires with weight ratings of 3,750 pounds on a 3/4 ton and a one ton truck, regardless of what was added to beef things up, isn't the max payload of both trucks 7,500 pounds? Isn't the tire ratings usually the weak link in max weight capability in heavy duty trucks?

Personally, I stopped looking at Letter Grade Ratings. It's an outdated system based on when they made stronger tires by adding more plys to the tire.

Look for Load Ratings that meet your needs.

But it's also the springs in many cases that are also a limiting factor. The axle itself is usually the same. The GAWR is the weakest link in the rear suspension, not necessarily the axle itself.

[StirCrazy]

when I bought mine to get the 11500 gvw package you had to get the 20" wheel option otherwise you could only get a 11000 gvw truck. it came with 20" BFG all terain ta's from the factory, I now have 20" Sailun terramax on it for the last two sets of tires.

Steve