Forum Discussion

noteven's avatar
noteven
Explorer III
Mar 09, 2015

Pickup truck tow vehicle stability tests

Always lots of anecdotal statements on rv.net around dual wheel vs single rear wheel "stability".

Anyone have any links that point to actual testing results under controlled conditions?
Tow Vehicles
  • Arcamper's avatar
    Arcamper
    Explorer
    Mar 13, 2015
    AH64ID wrote:
    Arcamper wrote:
    This topic really surprises me that anyone who has ever towed heavy would say 4 rear wheels are no better than 2. I just did a test myself out in our company parking lot. Parked my 3500 DRW next to a coworkers new 3500 SRW. Put my hand on the bed pocket above the rear wheel and pushed hard on both trucks. The SRW truck I could push about 3/4 inch back and forth. My DRW I could not move at all. It was all in the tire sidewall so I thought maybe his tire pressure was lower. Mine are at 65 and his were 70. After this controlled test I realized a DRW is more stable than a SRW of the same make and year.(How's that for scientific) LOL


    While the suspensions on the two trucks should be the same, assuming not a lot of weight in the DRW or suspension enhancements there is something not right about that test.

    DRW stability compleatly aside, I have a very hard time believing you can quantify the difference in tires and suspension and get 3/4" of tire squish (a tire rated for at least 3500lbs with 87% of its air) by pushing on the stake pocket.

    I can put 2000lbs in my bed and not get 3/4 of tire squish, and I am doubting you are putting 1000lbs of load on a stake pocket with your hands and not moving the suspension.


    Yes a DRW is more stable, but not for the reasons man think. The analogy about standing with your feet spread is pretty useless in this situation. Here is a way to test that it's useless with a floorjack and a pair of Jack stands. Jack up the rear off a DRW and put the jackstands under the springs, and apply a known force to the truck (maybe a spring scale to the tiedows in the bed) and measure the deflection with a jig. Move the jacktands 10" narrower and repeat. I'll bet you get the same reading, as it's the suspension that is deflecting despite the narrower width of the jacketsands.

    4 side walls make a huge difference in deflection, as does the increased spring rate with a good load applied.


    We did not put downward force on the trucks it was side to side force. I agree downward force could not be done by hand. I have 1840 lbs of pin weight and it drops my truck 1.5 inch's. Fact is though push side ways on the bed of a SRW and a DRW and you will see a difference.
  • AH64ID's avatar
    AH64ID
    Explorer
    Mar 13, 2015
    Arcamper wrote:
    This topic really surprises me that anyone who has ever towed heavy would say 4 rear wheels are no better than 2. I just did a test myself out in our company parking lot. Parked my 3500 DRW next to a coworkers new 3500 SRW. Put my hand on the bed pocket above the rear wheel and pushed hard on both trucks. The SRW truck I could push about 3/4 inch back and forth. My DRW I could not move at all. It was all in the tire sidewall so I thought maybe his tire pressure was lower. Mine are at 65 and his were 70. After this controlled test I realized a DRW is more stable than a SRW of the same make and year.(How's that for scientific) LOL


    While the suspensions on the two trucks should be the same, assuming not a lot of weight in the DRW or suspension enhancements there is something not right about that test.

    DRW stability compleatly aside, I have a very hard time believing you can quantify the difference in tires and suspension and get 3/4" of tire squish (a tire rated for at least 3500lbs with 87% of its air) by pushing on the stake pocket.

    I can put 2000lbs in my bed and not get 3/4 of tire squish, and I am doubting you are putting 1000lbs of load on a stake pocket with your hands and not moving the suspension.


    Yes a DRW is more stable, but not for the reasons man think. The analogy about standing with your feet spread is pretty useless in this situation. Here is a way to test that it's useless with a floorjack and a pair of Jack stands. Jack up the rear off a DRW and put the jackstands under the springs, and apply a known force to the truck (maybe a spring scale to the tiedows in the bed) and measure the deflection with a jig. Move the jacktands 10" narrower and repeat. I'll bet you get the same reading, as it's the suspension that is deflecting despite the narrower width of the jacketsands.

    4 side walls make a huge difference in deflection, as does the increased spring rate with a good load applied.
  • noteven's avatar
    noteven
    Explorer III
    Mar 13, 2015
    It's too bad the collective contributors to this thread are scattered all over the continent...

    We could do a crowd sourced project and engineer a proper set of tests -
  • valhalla360's avatar
    valhalla360
    Navigator
    Mar 13, 2015
    Arcamper wrote:
    This topic really surprises me that anyone who has ever towed heavy would say 4 rear wheels are no better than 2. I just did a test myself out in our company parking lot. Parked my 3500 DRW next to a coworkers new 3500 SRW. Put my hand on the bed pocket above the rear wheel and pushed hard on both trucks. The SRW truck I could push about 3/4 inch back and forth. My DRW I could not move at all. It was all in the tire sidewall so I thought maybe his tire pressure was lower. Mine are at 65 and his were 70. After this controlled test I realized a DRW is more stable than a SRW of the same make and year.(How's that for scientific) LOL


    Unless you pushed them hard enough to get the wheels off the ground, all you felt was the stiffer springs of the DRW truck having less give. If you pulled the outer tires off the rims of the DRW truck, it wouldn't budge either. Most of what people are feeling as the difference is a stiffer suspension.

    If you are towing and hauling more than the SRW truck is rated for, by all means get a DRW to carry the extra load but when pulling a load within the ratings of a SRW, there is negligible difference in safety and handling.

    If you really want the best, you should be getting a full class 8 semi tractor as that is even more stable. I'm curious why the dually supporters didn't do the logical thing and move up to the better option?
  • blt2ski's avatar
    blt2ski
    Moderator
    Mar 13, 2015
    Answered from a pickumup standpoint. BUT< if one COULD get singles, with the same overall width as duals, same wt capacity etc. I this case, i doubt there would be a lot of difference!

    Marty
  • Cummins12V98's avatar
    Cummins12V98
    Explorer III
    Mar 13, 2015
    45Ricochet wrote:
    She stated the obvious conclusion that all 3500/350 DRW owners said. "Our training wheels matter :B "


    YEA, what he said!!!
  • 45Ricochet's avatar
    45Ricochet
    Explorer
    Mar 13, 2015
    She stated the obvious conclusion that all 3500/350 DRW owners said. "Our training wheels matter :B "
  • mdamerell's avatar
    mdamerell
    Explorer
    Mar 13, 2015
    06Fargo wrote:
    Always lots of anecdotal statements on rv.net around dual wheel vs single rear wheel "stability".

    Anyone have any links that point to actual testing results under controlled conditions?


    Well I could not find anything in a search so I wrote to Ford and received this response. My original email is on the bottom. If I receive more, I will share it.

    _________________________

    Hello Melissa,

    My name is Chermaine, I am from Ford`s Customer Relationship Center (CRC). I have reviewed your email requesting information the Single Rear Wheel (SRW) and Dual Rear Wheel (DRW) comparison.

    To assist you, I escalated your case to our Technical Subject Matter Expert. We are not aware of any specific studies that we could link you about your question. However, theoretically speaking, anything that has a wider base will always be more stable than something with a narrower base. The simple demonstration is standing with your feet together and have someone push you. It is easy to push you from your spot. Now, stand with your feet shoulder width apart and do the same test. It is much harder to be pushed over. This is also reflected in the towing guides. You can look under the gasoline engine options and see the same gear ratio for SRW versus DRW. The DRW always has a higher tow rating.

    Thank you for contacting Ford Motor Company.

    Sincerely,

    Chermaine
    Customer Relationship Center
    Ford Motor Company

    Should you feel that we have not adequately addressed your inquiry, we may require additional information, please feel free to contact us via telephone at (800)392-3673 between the hours of 8:00 a.m. - 8:00 p.m. EST (Monday-Friday) / 9:00 a.m. - 5:30 p.m. EST (Saturday). Hearing-impaired callers with access to a TDD may contact 1-800-232-5952. Your reference number is CAS-6093539-P5F3G4.

    In addition, you can try online support at www.owner.ford.com. Here you can find answers to frequently asked questions (FAQs) and links to other key product and service information.

    Ford Confidentiality:
    --------------------
    For security reasons, please DO NOT submit any sensitive personally identifiable information (PII), such as credit card numbers, driver license number, SSN, DOB, etc. Thank you
    ------------------- Original Message -------------------
    From: GENERIC - CRC CONTACT
    Received: 3/10/2015 7:36 PM
    To: Tier 1 Email - CRCFMC
    Subject: Other

    Questions/Comments: On the RV boards there is often a debate over DRW vs SRW stability, pros and cons. Normally in regards to towing large 5th wheel campers. Example: a 15,000# 5er has a pin(hitch) weight of about 3,000# The 2014 F350 SRW or DRW can both handle the cargo capacity of carrying a 3,000# pin (hitch) but which truck will be more stable? Has there been a stability test comparing the SRW vs the DRW in different conditions and environments. High wind, stopping dry and wet pavement, grades, curves, etc... Other than the higher cargo capacity of the DRW is there an advantage over the SRW? Any documentation or videos of testing I can share on the RV boards would be awesome.

    Contact Information
    First Name : Melissa
  • NC_Hauler's avatar
    NC_Hauler
    Explorer
    Mar 12, 2015
    IdaD wrote:
    NC Hauler wrote:
    "I know there are narrow roads and mountains back east. The roads I'm contemplating that aren't so good for duelly's are the unimproved variety with lots of rocks and ruts, often with a rather unforgiving drop on one side into a ravine or river. There are full size trucks on these roads but very few are DRW. "


    Then if you know what's here in the east...the roads I'm talking about also have sheer cliffs on one side, (back up if you run into some one), and drop offs into ravines with raging rivers or streams...same thing.....but I know, it's just NC, TN, WV and VA...nothing like Idaho...

    Hey, I'm tired of arguing the point, you win.....your roads are impassable...no way could I drive or tow on them...BUT, I also have enough common sense to not take a 39' 9" high profile 5er on one of those type highway's, though I haven taken a 3/4 ton towing a 27' TT into some ravines that might make you even happy about it.

    you win....I need to avoid Idaho like the plague and you already know what it's like around here and probably could do it blindfolded...your point is taken.....


    I'm not trying to win anything, I'm just pointing out that DRW trucks have some substantial limitations for some people such as myself. The company I work for has several locations in the south (including two in North Carolina), so I travel down to that part of the country at least once a year and am pretty familiar with it. A lot of it is really scenic too - in particular that eastern part of NC is gorgeous. When you get a little further south and things flatten out I'm not as sold, though. The only time I can see any distance in Florida is on highway overpasses. Talk about flat...


    Don't spend any time in the eastern part of NC, have gone to the beach a couple of times, other than that, too flat, and to me not very scenic at all, nowhere near as nice as being in the mountains,...I'm in the mountains of Western North Carolina not far from the TN border and Smokey Mountains., then South western part of VA,(still in the mountains), and just about anywhere you go in WVa, you're in the mountains....

    nope, don't care for flatland...drove across TX from Texarkana to El Paso once and if it hadn't been for the Guadalupe Mountain range near and around El Paso, it was a most boring drive..prefer the mountains....and where I spend 99% of my time and towing, is in nothing but the mountains....

    ...Did almost all my off roading in Jeep's and a 72 Chevy 1/2 ton that had a 350 in it, a liftand tall, knobby tires and it couldn't touch my Jeep J-20 that I had for a while...best ever was an old Army Jeep I got from my brother in law....that thing was amazing, but now I'm talking about 23 years ago...

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