Dual Rear Wheels and Mild Off-roading - Is it Really That Bad?

[1000arms]

Please be aware that the Three-Peak Mountain Snowflake Symbol only indicates a minimum performance standard.

"In 1999, The U.S. Tire Manufacturers Association (USTMA) and the Rubber Association of Canada (RAC) agreed on a performance-based standard to identify passenger and light truck tires that attain a traction index equal to, or greater than 110 (compared to a reference tire which is rated 100) during the specified American Society for Testing and Materials traction tests on packed snow. The standard is intended to help ensure drivers can easily identify tires that provide a higher level of snow traction, and tires meeting that standard are branded with the three-peak mountain snowflake (3PMSF) symbol.

Some important information to remember about 3PMSF branding.

Testing measures a tire's acceleration traction on medium-packed snow only. Braking and turning on snow, along with ice traction are not components of the test.
Tires branded with the 3PMSF symbol are expected to provide improved snow traction beyond a standard M+S branded all-season tire, however 3PMSF-branded all-season and all-terrain tires cannot match the traction of dedicated winter / snow tires in all winter weather conditions and should not be considered a replacement for where and when a dedicated winter tire is needed." From: https://www.tirerack.com/upgrade-garage/what-is-the-threepeak-mountain-snowflake-symbol

Depending on where you will be driving, having tires with the Three-Peak Mountain Snowflake Symbol will likely be useful, but I would suggest choosing Three-Peak Mountain Snowflake Symbol tires that greatly exceed the "traction index equal to, or greater than 110" mentioned in the quote.

Depending on where one lives and drives, one might want to consider dedicated winter tires.

Having tire chains, and knowing how to use them, can be quite helpful in snow/ice and mud. ... Check out: https://bangshift.com/bangshiftxl/l...rator-save-another-machine-frozen-lake-maine/

Thanks, good stuff to know. Out west my experience and those of friends is that tires with that symbol perform amazingly well. We mostly deal with snow and rarely really icy conditions. If the roads are really icy the skiing probably isn't great so no need to go anywhere! And I always carry chains in winter.

Some Three-Peak Mountain Snowflake Symbol tires are much better in snow than others. It appears that you and your friends are using the better ones.

I suspect that some dry-powder skiers and snowboarders would wince at what people ski and board on in the New England states. I've seen people happily using skis and snowboards on slush-ice at Tuckerman Ravine (Mount Washington) in late July. They were planning to hike back up in August to do so again.

Tuckerman Ravine - Wikipedia

en.wikipedia.org

Tuckerman Ravine · Sargent's Purchase, NH 03846, USA

★★★★★ · Ravine

www.google.com

 

[Metcalf]

I ran DRW F350-450 BLM Wildland Fire Engines around for 6 years in a past life. Running dually rear tire packages created more problems than it solved in my opinion. We tried for years to get them to let us try a super single style setup. They just kept buying us tires....and we went through a lot of them, especially with newer drivers or pushing the trucks harder off road.

Some things to think about....

-The front and rear tire track much different. If you just miss the rock with the front tires....the rear tires are probably going to get hit.
-Rocks between the tires is a constant concern and headache
-Changing inside rear tires sucks
-Tire choices are more limited because of the dual rear tire
-Airing down the tires is limited because of the dual rear tire

 

[AbleGuy]

⬆️ x 2

Some things to think about....

-The front and rear tire track much different. If you just miss the rock with the front tires....the rear tires are probably going to get hit.***
-Rocks between the tires is a constant concern and headache ***
-Changing inside rear tires sucks
-…,
-Airing down the tires is limited because of the dual rear tire***

***Our experience too with our 1ton van running duallys.

And frankly, on really narrow paved two lane roads running a rig with wide side mirrors, we often dragged the outside rear passenger side tire off the asphalt and onto the debris laden shoulder when passing by another approaching vehicle!

 

[CoyoteThistle]

I ran DRW F350-450 BLM Wildland Fire Engines around for 6 years in a past life. Running dually rear tire packages created more problems than it solved in my opinion. We tried for years to get them to let us try a super single style setup. They just kept buying us tires....and we went through a lot of them, especially with newer drivers or pushing the trucks harder off road.

Some things to think about....

-The front and rear tire track much different. If you just miss the rock with the front tires....the rear tires are probably going to get hit.
-Rocks between the tires is a constant concern and headache
-Changing inside rear tires sucks
-Tire choices are more limited because of the dual rear tire
-Airing down the tires is limited because of the dual rear tire

Thanks for those points - good ones. Interesting to hear different experience with rocks between the tires than some others so far. I wonder if in the course of that type of work you wound up on some pretty rough terrain compared to what I'd ever want to do.

Why is changing the inside tire so bad?

I agree that the limitation in airing down tires is a minus - it really helps smooth out the ride on washboard roads for instance. I imagine it depends on space between tires, choice of tire, and weight on the rear axle as to how much deflation one can get away with. In practice I guess this just leads to slower driving in certain situations.

 

[CoyoteThistle]

⬆️ x 2


***Our experience too with our 1ton van running duallys.

And frankly, on really narrow paved two lane roads running a rig with wide side mirrors, we often dragged the outside rear passenger side tire off the asphalt and onto the debris laden shoulder when passing by another approaching vehicle!

I believe on the Sprinter the rear track width is the same with SRW and DRW (or very close) so shouldn't be a problem. Thanks for the X2 on the no bueno vote, appreciate all the input!

 

[BikePilot]

MB Sprinter AWD cab chassis is only available with DRW. 10k is my current rough estimate of truck, camper, gear, etc.

Gotcha! I thought you were talking about a truck camper. That makes sense. I don't think dual wheels are going to be a limiting factor when taking an AWD sprinter off pavement.

 

[AbleGuy]

I agree that the limitation in airing down tires is a minus - it really helps smooth out the ride on washboard roads for instance. I imagine it depends on space between tires, choice of tire, and weight on the rear axle as to how much deflation one can get away with.

+ we really liked the added stability of the duallies and the added weight carrying capacity. On winding roads the ride was a more confident, felt more secure and driving was much less stressful because the side to side sway was so greatly reduced by the wider footprint of the dual tires.

- we ran a fatter tires on the rear and the gap between the dual tires at pavement was way too small. If they were not aired up perfectly properly the sidewalls could actually rub. On sharp shaley or cracked chert rock forestry roads, getter pointy shards lodged between the tires was a constant problem and because of the tight narrow gap it was very difficult to dislodge the rocks. In hindsight it would have been better if we had run on skinnier dual tires

 

[Metcalf]

Thanks for those points - good ones. Interesting to hear different experience with rocks between the tires than some others so far. I wonder if in the course of that type of work you wound up on some pretty rough terrain compared to what I'd ever want to do.

Why is changing the inside tire so bad?

I agree that the limitation in airing down tires is a minus - it really helps smooth out the ride on washboard roads for instance. I imagine it depends on space between tires, choice of tire, and weight on the rear axle as to how much deflation one can get away with. In practice I guess this just leads to slower driving in certain situations.

Changing the inside tire requires taking the outside tire off also. It is just extra stuff and extra steps to manage. Having dually rims 'stick' in place is also pretty common.

Being able to air the tires down goes FAR beyond ride quality. A vehicle with properly aired down tires will be more capable than one at street pressure, it doesn't matter if you have all the other gadgets...lockers, gearing, etc....air pressure makes an exponential difference in rubber tired vehicle mobility off-road.

 

[1stDeuce]

Lots of good points here... I'm bored so you get my thoughts too...

It doesn't sound like you are planning to get crazy off road, only do some back road driving... For that reason, I'd say you'll be fine with a dually. Three of our brush trucks are duallies, and they do fine. Because we don't run far down the road, I run the tires at a lower than recommended pressure. (Typically ~50psi in the fronts and 35-45 in the rears depending on the truck.) The rear tires do touch lightly on two of the trucks, but we've never had a problem because of it. I would not run them great distances like this, but for our use, the pressure is "proper" IMO.

Airing down properly helps ALL things offroad, from ride to traction to tire life IMO. Airing down dually tires can be a bit more work, as it is often a bit more difficult to get to the valve stem of the inner dual. There are harnesses that connect the duals together and equalize pressure and make one place to air them up/down. If you have TPMS, those kits make sense. Without it, you're just going to flatten both tires if one springs a leak...

We have one truck with 19.5" wheels. I would not recommend 19.5's for even mild off road use... 19.5's are similar to the old 16.5" wheels, with only a tapered bead seat area. The tire is kept in place only by the air pressure within, so a bit of side loading can push the bead inward and all the air whooshes out and you have an instant flat... Non-XX.5" wheels have a flat area where the bead seats, as well as a retaining feature that helps them stay on the wheel at low pressures. I run our 19.5" truck at no less than 50psi, and traction off road suffers greatly compared to the trucks running 16" wheels at a lower, more appropriate pressure.

I have found that for winter use, the 3PMS rating does help considerably, but performance does vary... I have some Goodyear Ultraterrains that I would bet are almost as good as the best winter tire, and certainly great for a truck in the winter, while the same size BFG AT's that also have the 3PMS symbol are not as good in general. That said, both of the 3PMS tires are noticeably better than the Cooper AT3's that I ran before, which were not 3PMS. If you drive in snow at times, a 3PMS tire is the ONLY way I would go, and there are some great choices!!

In the wide open desert, the extra width of a dually isn't that critical, but if you plan to get into forest roads, it's something to consider. You pretty much have to park WAY out in the parking lot at any big store too, as a CC dually does't fit in a normal sized parking spot that well... There's a reason why so many ranch trucks that are duallies have busted fenders...

 

[CoyoteThistle]

Lots of good points here... I'm bored so you get my thoughts too...

Thanks for sharing, more good experience and perspective!

Didn't know about the ability to connect the duals to make one air up/down point - does sound worth looking into. Four rounds with the compressor sounds quicker than six.

One of the things I like about the platform I'm looking at is that the DRW version isn't any wider than the SRW so just the normal width limitations of a full size rig. It'll be 22+ft long so I'll be parking way out in the nether regions anyway

 

[1000arms]

I ran DRW F350-450 BLM Wildland Fire Engines around for 6 years in a past life. Running dually rear tire packages created more problems than it solved in my opinion. We tried for years to get them to let us try a super single style setup. They just kept buying us tires....and we went through a lot of them, especially with newer drivers or pushing the trucks harder off road. ...

... I've seen plenty of dually ranch vehicles on a wide range of dirt roads out west here - where there are rocks and snow. ...

95% of driving will be on highways where the extra stability of DRW sounds like an advantage. ...

@Metcalf, for the driving the OP @CoyoteThistle has mentioned, do you think rocks between the DRWs would be a common issue, something to be aware of, ... ?

 

[Metcalf]

@Metcalf, for the driving the OP @CoyoteThistle has mentioned, do you think rocks between the DRWs would be a common issue, something to be aware of, ... ?

Yes, it happened all the time on the light engines. We would get rocks stuck in the duals just driving around on regular BLM/FS roads.

Everyone that operated an engine was taught to check the duals often and how to remove rocks using the 'chain' method where you loop the rock and back over the chain with the front tire to pull it out.

We constantly fought tire issues, especially on the F450s with the larger rims ( 19.5s? ) as we had a very limited selection of tires to choose from. Finding tires with even an all terrain tread pattern was tough back then. That might be better now, but size selection with dual rear wheels is always going to be an issue.

 

[1stDeuce]

Thanks for sharing, more good experience and perspective!

Didn't know about the ability to connect the duals to make one air up/down point - does sound worth looking into. Four rounds with the compressor sounds quicker than six.

One of the things I like about the platform I'm looking at is that the DRW version isn't any wider than the SRW so just the normal width limitations of a full size rig. It'll be 22+ft long so I'll be parking way out in the nether regions anyway

If I may inquire, what platform are you looking at that has a DRW that's no wider than SRW? The only thing I can think of that fits that description is a sprinter van... If it's not wider, then stability is not improved with the DRW, and I'd opt for SRW to avoid the other issues with running a DRW... ???

 

[1000arms]

Yes, it happened all the time on the light engines. We would get rocks stuck in the duals just driving around on regular BLM/FS roads.

Everyone that operated an engine was taught to check the duals often and how to remove rocks using the 'chain' method where you loop the rock and back over the chain with the front tire to pull it out.

We constantly fought tire issues, especially on the F450s with the larger rims ( 19.5s? ) as we had a very limited selection of tires to choose from. Finding tires with even an all terrain tread pattern was tough back then. That might be better now, but size selection with dual rear wheels is always going to be an issue.

Thanks. ... What BLM/FS roads (if you don't mind sharing)?

 

[Metcalf]

Thanks. ... What BLM/FS roads (if you don't mind sharing)?

Over 6+ years on engines I operated all over the country.....thousands of miles all over the western USA.
My home base was around the Salmon/Challis National Forest and the BLM lands in that area.