DRW vs SRW safety, tire blowout

[AH_AK]

Every time the DRW vs SRW debate starts up, dually owners always point to the safety of having 4 rear wheels in case of a blowout while driving. What I am wondering is has anyone actually experienced (or have first hand knowledge of) a SRW blowout that ended in a catastrophic outcome (e.g. crash)?
Obviously, the DRW is going to have better lateral stability
in cornering/cross winds compared to the SRW, but I am only considering the blowout safety aspect. While the redundant tire safety argument is logical, I am wondering how likely such blowout situations are.
To be clear, I am talking about SRW that are not exceeding the maximum tire load, are correctly inflated, and being driven within the tire speed limit. I am running 19.5’s with Firestone AT3’s so I am in this category. I realize most SRW truck camper owners are over their max tire load and yet, there is little to no documentation of blowout failures despite the obvious overloading. It makes me think the DRW blowout safety argument is essentially moot, even though it is totally logical.

[Grit_dog]

KKELLER14K wrote:
You nailed it...I'm not a basher but those are the Toyo HT. Just bad tires. Good call deserteagle56. You know the brand and type to avoid. We have been down that road on bad tires. I was already leary after two other gave outs and it was definitely time to change it up. They were at about 50% anyway so it was a no-brainer.

So now Toyo = bad? Lol. They’re literally one of the highest quality tires produced currently.
Were yours and the other guys tires not part of the recall on Toyo HTs?

Or were they and you guys were unaware or possibly it happened before the recall and your tires are part of the reason for the recall?

[Lantley]

Lantley wrote:
No dog in this fight but actual experience always supersedes text book theories
My dually is more stable than my SRW trucks.
Is it the out rigger effect or is it stiffer sidewalls? Does it matter? From the drivers seat I can feel a noticeable difference.
My dually also has more braking power, it certainly stops my trailer much faster the my SRW trucks. Again this is determined from the drivers seat not from the text book.

Yes but I have 2 extra tires transferring that braking force to the ground.
For the same reason I believe SRW trucks perform better in snow because they have less ground contact and dig/sink into the snow for better traction. DRW trucks have more ground contact and brake better. All my comments are from real encounters from the drivers seat not from trying to match part numbers or derived from what I think might happen.
Once you have experienced the performance first hand from the driver's seat, you no longer have to imagine what will happen.

[SoonDockin]

I feel more tires is better, also bigger is better. Its why I went from a F350 Single to a F450 Dually and now a 5500. F450 was super stable, 5500 takes it to a whole new level.

[3_tons]

KKELLER14K said:

“ This is why I feel a tad bit safer having 4 rather than 2 under the rear load.”

Exactly, Nuff said…

3 tons

[srschang]

Think geometry for a moment.

With the same spring set and same load the DRW actually has MORE leverage against the spring set than the SRW does so the suspension will have more sway with a DRW then a SRW. (the pivot point is the center where the axle spring pack make contact and the leverage point is the outside of the tire)

However most will claim a DRW is "more stable" because twice as many sidewalls reduce the sidewall flex considerably. The reduction in sidewall flex is much greater than the additional suspension leverage resulting in reduced sway or "more stable" ride.

For SRW's switching to commercial rated tires with fairly to very stiff sidewalls is equally or more effective.


- Mark0.



Not sure what truck we are talking about, but on the Ram, more leaves on the DRW than on the SRW. And I switched to 19.5s on my 2020 Ram SRW. My 2022 Ram dually with the factory tires has less side to side sway than the 2020 with commercial tires.

[mbloof]

Lantley wrote:
No dog in this fight but actual experience always supersedes text book theories
My dually is more stable than my SRW trucks.
Is it the out rigger effect or is it stiffer sidewalls? Does it matter? From the drivers seat I can feel a noticeable difference.
My dually also has more braking power, it certainly stops my trailer much faster the my SRW trucks. Again this is determined from the drivers seat not from the text book.

Funny as if you look at the actual part numbers for the DRW and SRW breaks guess what?

They are the same.

So much for "seat of the pants" theories... 🙂

Enjoy your DRW, for whatever reasons you have.



- Mark0.

[greenno]

Gdog I have a hard time believing that I should be running 35psi in my rear tires.
I could probably drop the front a bit more but I'm thinking not 15psi.
I have pretty even wear across the tire tread so I know I'm close to having a flat surface on the road.
Side treads as well as the centers were about the same so it's not crowning.

[Lantley]

No dog in this fight but actual experience always supersedes text book theories
My dually is more stable than my SRW trucks.
Is it the out rigger effect or is it stiffer sidewalls? Does it matter? From the drivers seat I can feel a noticeable difference.
My dually also has more braking power, it certainly stops my trailer much faster the my SRW trucks. Again this is determined from the drivers seat not from the text book.

[mbloof]

Grit dog wrote:

3 tons wrote:

Bedlam wrote:
Since the frame pivots on the axle at same point of a DRW and SRW pickups, I think the stability comes more from sidewall stiffness and higher rated springs. Until you start picking up a rear wheel I do not feel the width plays a role.

Believe whatever you like…as I stated, not from pontification but from actual real back to back experience from having two identical trucks differing ONLY in SRW vs DRW, there IS an outrigger effect, but honestly I almost feel like I’m barking at the moon, so for those doubting Thomas’s enjoy your comfort providing paradigm and feel free to disregard…:)

3 tons

Think geometry for a moment.

With the same spring set and same load the DRW actually has MORE leverage against the spring set than the SRW does so the suspension will have more sway with a DRW then a SRW. (the pivot point is the center where the axle spring pack make contact and the leverage point is the outside of the tire)

However most will claim a DRW is "more stable" because twice as many sidewalls reduce the sidewall flex considerably. The reduction in sidewall flex is much greater than the additional suspension leverage resulting in reduced sway or "more stable" ride.

For SRW's switching to commercial rated tires with fairly to very stiff sidewalls is equally or more effective.


- Mark0.

[KKELLER14K]

You nailed it...I'm not a basher but those are the Toyo HT. Just bad tires. Good call deserteagle56. You know the brand and type to avoid. We have been down that road on bad tires. I was already leary after two other gave outs and it was definitely time to change it up. They were at about 50% anyway so it was a no-brainer.

[Grit_dog]

greenno wrote:
Not to beat a dead horse her e but I do agree sidewall stiffness makes a difference.
I am running the Toyo MT's 35 x 12.5 x 18 tires at 80psi when loaded up and around 65 around town so I don't get beat up.
I think they have an "F" load rating.
Unfortunately no warranty comes with these tires and at about 5 bills each that sucks.
I have a little over 20k miles on them and the trad depth started off at 21/32" and I measured a couple of days ago and their averaging about 10/32" so their probably 2/3 gone at this point.
Im guessing I will be replacing in about a year or so with only about 30k miles on them.

For my piece of mind I'm ok with that trade off.

Now lower the “around town” pressure. Betting you’re at 10/32 center of tread and more on the outer lugs. That’s 10-15psi too high on the front of a diesel and 30+psi too high on an unloaded rear axle.
And your kidneys and ball joints will also thank you for it.

[greenno]

Not to beat a dead horse her e but I do agree sidewall stiffness makes a difference.
I am running the Toyo MT's 35 x 12.5 x 18 tires at 80psi when loaded up and around 65 around town so I don't get beat up.
I think they have an "F" load rating.
Unfortunately no warranty comes with these tires and at about 5 bills each that sucks.
I have a little over 20k miles on them and the trad depth started off at 21/32" and I measured a couple of days ago and their averaging about 10/32" so their probably 2/3 gone at this point.
Im guessing I will be replacing in about a year or so with only about 30k miles on them.

For my piece of mind I'm ok with that trade off.

[deserteagle56]

jimh406 wrote:
That tread separation is pretty strange. I agree that it's time to change brands.

Absolutely the brand.

A few years ago I put 6 new Toyo H/T Touring (same as shown in the above pics) on my dually. A few months after installation I got a recall notice, told me to bring the truck back to the dealer so they could check the batch numbers because certain batches were have tread separation issues. Which I did; dealer told me my tires were not covered by the recall and I was good to go.

Since then I've had tread separations on two of the Toyos. I had to pay for the replacements - no warranty coverage at all. Dealer and Toyo refuse to replace the other four tires even though they have barely 20,000 miles on them, and I expect they will fail also.

But it is just this particular model of Toyo tire. I've run Toyo Open Country Mud Terrains for years now on my very heavy 4x4 van; they are all chewed up now because of rocks but I've never even had a flat on one.

[jimh406]

That tread separation is pretty strange. I agree that it's time to change brands.

Of course, you have an extra safety margin with 19.5 Gs on a F450 or similar. The tire structure is much stronger. Sure, you pay for it in ride quality.

[Grit_dog]

3 tons wrote:

Bedlam wrote:
Since the frame pivots on the axle at same point of a DRW and SRW pickups, I think the stability comes more from sidewall stiffness and higher rated springs. Until you start picking up a rear wheel I do not feel the width plays a role.

Believe whatever you like…as I stated, not from pontification but from actual real back to back experience from having two identical trucks differing ONLY in SRW vs DRW, there IS an outrigger effect, but honestly I almost feel like I’m barking at the moon, so for those doubting Thomas’s enjoy your comfort providing paradigm and feel free to disregard…:)

3 tons

Except Bedlam is right. Until the springs flex enough to put the C of G out past the edge of a srw tire, both chassis’s react the same if they have the same spring rate. However 6klbs of tire capacity vs 3500-4000lbs best case is a minimum of 50% greater carrying capacity and subsequently less tire flex.
The outrigger effect is due to the stiffness of the tires and it’s real. It’s just not due to the width until the above happens.

Just like the “dooleys stop faster” theory. Only true once you reach the threshold of traction on the srw tire.
All other things equal, a Dooley weighs more and has more rotating mass to control. Therefore the same brake pressure has slightly less net effect on a dually.