SRW vs DRW

[pressure_welder]

Good morning everyone hope your all doing well, So just recently we built a home off of a lake we used to camp at regularly, by doing that we've cut our camping in maybe half.... we spend our usual 1 month trip up at our favorite lake every year though, so our towing needs has decreased significantly, so i actually got rid of our 2015 ram 3500 limited drw about 2 years ago now just because i couldnt justify it carrying my butt around 90% of the year as a grocery getter. So for last two years ive been using the welding truck to pull our rig to the lake 2007 5.9 quad cab, with G56. The truck handles the load perfectly fine, its no rocket ship but it does quite well, on a side note the reverse gear on the G56 is HORRIBLE, your either riding the clutch the whole time or are a race car driver, geared way to high.

Anyway, the welding truck isnt horribly family friendly with the quad cab, and looking into weather or not a SRW 3500 would actually fill our needs accordingly, more comfortable for the family, easier daily driver, and a little more justifiable to own than a dually year round as my personal vehicle. Our situation is a bit different and i am not sure how to read it. We pull our camper and boat in tandem and here are the specs.


2018 montana 305RL - 14,270LBS loaded weight, 2395lbs pin weight

19FT crestliner sportfish - 3800LBS loaded weight/trailer, 300LBS tounge weight. on a tandem axle trailer, 23FT overall length


so with these numbers gets us in around that 18,000LBS total mark. However if i just had the fifth wheel a SRW 3500 should handle that without issue.... ive always thought of the boat as dead weight when in actuality its just rolling resistance of course until your stopping. Would i be correct to say that just adding the toungne weight of the boat to the camper weight, and maybe even 1000lbs extra for rolling resistance, would have me still safely within a SRW 3500 towing capacity?

all in all our main focus is to just acquire somthing more practical to own year round, and not have to use the welding truck to haul the rig up to the lake. Personal vehicle at the moment is a laramie eco diesel which is an amazing commuter, but i do miss my 6.7

[pressure_welder]

You know guys... not sure why iam so concerned with going to a srw... on a pipe job today figured id check payload capacity of my 07 5.9, yep! 4705lb payload and 15,750 max tow so iam already pushing the hell out of this dually. When were pulling camper/boat we MIGHT be within that max tow number as boat is rolling resistance. But as for payload.... lol. I have my tool boxes with maybe 250lbs of tools, 60 gallons in slip tank, oxy/acet bottles, 900lb welder, andersen hitch if that even counts at 30lb, and of course a 1000lb welding bed. I have air bags so she sits level, and truck still handles rig perfectly fine. But 2017 and up srws certainly “as a rule” have more payload and towing capacity than i currently have, and garunteed better braking. Only thing they wouldnt have is stability lf dually

In reality ive towed alot more than our camper/boat on our 40ft gooseneck.

[blofgren]

Sagebrush wrote:
Your also not pushing the rear tire's load ratings of a DRW like a SRW. Even with a 4k or 5K pin weight. Using the tire load charts or even the truck's door sticker for max payload I've never needed to air up my DRW to the tire's 80 psi max. My max payload rating needs 65 psi in the tires. Its nice to have those rear tires well within their load capacity.

Yep, and the lower pressure in the rear tires makes for a better riding truck.

[blt2ski]

Assuming we are disCUSSing DOT class three trucks,a DW will stop and carry more than a single wheel setup.

If you want to disCUSS class 8 trucks DW vs super singles. The singles win!

So assuming both rear axles have the same braking, springs, tire capacities, same sq inches of tire on the road, singles are better generally speaking

Marty

[fj12ryder]

Lantley wrote:
...
The discussion doesn't have to be so complicated.
Remember this is the towing forum. The DRW will brake better than a SRW while towing a heavy load under similar conditions.

It gets complicated because not everyone believes as you do. Lots of different opinions. Yours is just one...which I happen to agree with.

[Lantley]

Boy we can get off track. Will a SRW make a better Mars Rover? What happens if the streets are full of molten Lava?.....We don't need to examine kinds of "What if's"
The discussion doesn't have to be so complicated.
Remember this is the towing forum. The DRW will brake better than a SRW while towing a heavy load under similar conditions.

[Mike134]

fj12ryder wrote:
I believe the basic premise is, all things being equal: tires, surface, brakes, etc., a DRW will stop shorter than a SRW. Yes, there are tons of different parameters, but ignore them and consider everything is the same for both trucks.

Heck, pull two of the rear duals, check the sopping distance, put the duals back on and recheck the stopping distance over the same surface. That should give a decent answer?

Best answer so far.

[fj12ryder]

I believe the basic premise is, all things being equal: tires, surface, brakes, etc., a DRW will stop shorter than a SRW. Yes, there are tons of different parameters, but ignore them and consider everything is the same for both trucks.

Heck, pull two of the rear duals, check the sopping distance, put the duals back on and recheck the stopping distance over the same surface. That should give a decent answer?

[BenK]

Double sigh...

There are many other variables that come into play that this discussion hasn't even touched on.

Like the crevices of asphalt pavement comes into play. when tire compound gets mushed into them...coefficient of friction is not in play. As it is now interference & potential tearing of the compound off of the tire...or pulling out that gravel/stone from asphalt.

There is also a temperature component and not what one might think. It has to do with the boiling of tire compound during a skid or extremely high rate of change between pavement and tire compound...it can and does boil the tire compound for an instant to lay down those black marks that only come off over time via wear.

How's about the braking system components...like the brake's friction material ?

And etc, etc...

Not all of these kinds of tests are with EVERYTHING the same.

philh wrote:
{sigh}

This is not a simple friction equation. In general, given the same weight, frictional forces do not change with contact area.

Turn off traction control and I can guarantee the brakes will lock up the wheels, no matter if it's DRW or SRW

Where it really gets complicated, unloaded DRW, vertical load on contact area is less than SRW. Loaded, the weight increase means DRW will stop faster... but even that gets confused with trailer brakes entering the picture. I most certainly wouldn't to do a panic brake stop without trailer brakes, jack knife comes to mind.

This is best seen on snowy surfaces, wider tires have lighter vertical load and subsequently less traction.

Bottom line, while towing, DRW has the capacity to stop in a shorter distance on dry roads. While not towing, SRW might stop faster.

Plus there are FMVSS MINIMUM stopping distance spec's for all automotive

So splitting hairs, as all OEM vehicles has to meet DOT/FMVSS guidelines.


This image from their site years and years ago and assume the distances listed have changed

Click For Full-Size Image.

[Devo_the_dog]

Mike134 wrote:
It goes to show how worthless internet info can be unless you drill down and verify. Sorta like the "facts" you hear boasted at the local gin mill after the patrons have had a few to many.

I know what you mean. But, internet info isn't the problem. It's the lack of comprehension and basic reading skills.

[philh]

{sigh}

This is not a simple friction equation. In general, given the same weight, frictional forces do not change with contact area.

Turn off traction control and I can guarantee the brakes will lock up the wheels, no matter if it's DRW or SRW

Where it really gets complicated, unloaded DRW, vertical load on contact area is less than SRW. Loaded, the weight increase means DRW will stop faster... but even that gets confused with trailer brakes entering the picture. I most certainly wouldn't to do a panic brake stop without trailer brakes, jack knife comes to mind.

This is best seen on snowy surfaces, wider tires have lighter vertical load and subsequently less traction.

Bottom line, while towing, DRW has the capacity to stop in a shorter distance on dry roads. While not towing, SRW might stop faster.

[Sagebrush]

Your also not pushing the rear tire's load ratings of a DRW like a SRW. Even with a 4k or 5K pin weight. Using the tire load charts or even the truck's door sticker for max payload I've never needed to air up my DRW to the tire's 80 psi max. My max payload rating needs 65 psi in the tires. Its nice to have those rear tires well within their load capacity.

[Grit_dog]

Devo the dog wrote:

Travlingman wrote:
Here is a challenge that Pickuptrucks.com ran on 2018 1 ton SRW and then 2017 1 ton DRW where they did a braking challenge from 60 MPH to 0.

1 ton SRW:
Chevy - 165.3 feet
Ford - 158.3 feet

1 ton DRW:
GMC - 133.39 feet
Ford - 139.68 feet

The DRW test was done on a drag strip (Las Vegas motor speedway).
The SRW test was done on a dusty airport runway in Kingman AZ.

Those are two completely different surfaces. LOL.

Aww snap! So maybe I’m not all sideways on this...
Thx for sharing Devo.

[Cummins12V98]

"It would be nice if they could get the vehicles for their test at the same time so the test would be in the same conditions."


I agree, I would also like them to fill to the top not the silly click method.

[fj12ryder]

All things being equal, i.e. tire sizes, on the trucks. A DRW will have a roughly 50% larger overall contact patch compared to a SRW. But the weight difference will be roughly 30% less per contact patch. To me that would indicate the DRW would stop quicker, all things being equal.

Common sense would seem to indicate the DRW would stop quicker, but when it comes to physics, common sense sometimes isn't so common. 🙂 But I still think the DRW will stop in a shorter distance.