Wheelbase and towing (again !!)

[Frank C]

I suppose there are many good suggestions here, varying from sublime to ridiculous. I've towed with SUVs very successfully, first a '97 Expedition, then a '00 Durango, and once with my son's Toyota Tacoma. Though the SUVs might have softer suspensions, they are appropriately rated for a 5000 lb. towing, which means they are rated to handle the 350 to 400 pounds of tongue wt. However, A little common sense is helpful. The SUVs are obviously not going to do so while also carrying six adults.

My latest tow vehicle, a 2003 Sierra pickup 1500, can make me forget there's a load attached. That anyone would need to use a model 2500 (three-quarter ton) pickup to pull a Mac is extremist advice, to put it as politely as possible. Any full-size pickup, combined with the slightest smidgeon of common sense, provides ample torque, weight-rating and brain capacity for towing a Mac.

[Catigale]

Ive towed Catigale with my 2002 VW eurovan from Albany to Buffalo/Boston a total of 10 times so far. Its a front wheel drive van and I cruise about 60 mph in traffic (to minimise passing events), 65 if I am all alone. The Admiral will drive this combo and be comfortable in traffic - she is a real trooper but wouldnt do this if it were snarly.

I dont get blown all over the road when trucks go by (although I90 is heavily speed-trapped and average speeds tend to be in the 70 mph range.)

Am I doing something right by chance? Could a van possibly 'break the air' for the Mac and make the rig more stable than an SUV or truck?

I put as much stuff as I can in the V berth, and dont fill tanks (18 gallons) until I am near destination.

[Dimitri-2000X-Tampa]

The SUVs are obviously not going to do so while also carrying six adults.

Frank, your opinion is rather depressing. One of the biggest reasons I want a new tow vehicle eventually, is that I DO want to be able to put 6 people and a big load of stuff into an SUV and still be able to tow a Mac. With my Odyssey, you aren't supposed to have more than 2 adults in it when towing 3500#. I have been casually eyeballing Suburbans and Seqouia's at being up to the task...certainly by the spec numbers, they are...but why would you think that you can't put 6 adults into a (large) SUV and still tow a Mac satisfactorily?

I've driven a 90's vintage Ford 150 pickup truck before, it does not handle ANYWHERE as nicely as the Odyssey minivan does. Rear end slides out, its all over the road at speeds above 70 mph, etc...great for hauling wood though. I have avoided a deer on I-95 at 85mph in my Odyssey with 6 people aboard and I could have been driving a sportscar as nicely as it swerved...I don't think the F-150 would have made it (without some serious fishtail control moves). Durability issues aside, I think some of the "big truck" crowd in this bunch may be overlooking some of these basic performance issues in favor of pure brawn (larger frame, suspension, etc.). You all are making me seriously think about demanding a test drive towing a Mac with my whole family aboard before plunking down any serious cash on a big truck. Btw, the 2001 Odyssey is quite spartan...a luxury vehicle it is not, it has a pretty stiff suspension and the rear end does not sag nearly as much with a 3500# Mac on it as my old Dodge minivan did with an 1800# jetboat on it for example.

I didn't realize that the SUV's had shortened wheelbases either...I always figured they were built on the same chassis as their sister pickup trucks..ie Seqoia-Tacoma, Suburban-Silverado, etc.

[Moe]

Dimitri, with a large family, what you have to understand is that every 100 lbs of option, passenger, and cargo weight can reduce so-called "towing capacity" by 1,000 lbs, once you get beyond a certain point.

A 138.5" wheelbase F150 SuperCrew 4WD w/5.4L V-8 and 3.73:1 axles, has a 15,000 lb Gross Combined Weight Rating, and a "towing capacity" of 9200 lbs. Sounds like overkill for a MacGregor? This means Ford is considering the tow vehicle weight to be 5800 lbs.

It also has a 7200 lb Gross Vehicle Weight Rating, and a "payload" (includes options, people, cargo and fuel) of 1600 lbs. This means Ford is considering the vehicle weight to be 5600 lbs. So one could deduce "towing capacity" is calculated with 200 lbs for the driver, additional weight of the 5.4L option, and fuel, to get 5800 lbs. The driver is usually considered 150 lbs, the bigger engine probably 50 lbs, and no weight left for fuel in that 200 lbs.

Let's take our 5650 lb 5.4L SuperCrew, add 200 lbs for a full tank of gas (30 gal), and 150 lbs for a good camper top to make it like an SUV, and some tools. We've used 400 lbs of our 1600 lb payload, and are at 6,000 lbs, with 1200 remaining to the 7200 lb GVWR. Now lets put 6 people (and their "stuff") at a 150 lb average, or 900 lbs in there.

That leaves 300 lbs for hitch head and tongue weight, which translates into 3,000 lbs total trailer weight, i.e. remaining "towing capacity" at a 10% tongue weight... at best. If we cut the people and "stuff" load by 200 lbs, we have 500 for tongue weight, and thus about 5,000 lb actual towing capacity.

Hopefully, you can now understand why I'm recommending tow vehicles with 3-5 times the 3500 lb Class II "towing capacity."
--
Moe

[Moe]

BTW, Dimitri, your real-world test drive is exactly what I recommend for people shopping for an RV, or shopping for a tow vehicle for an RV.

I recommend that whether it's a new vehicle test drive, or evaluating an existing vehicle, that it be fully fueled, and loaded with all the people and cargo that would ever be in the vehicle while towing,

Then take the vehicle to a CAT scale or other certified scale. Pull up on it, trying to get the front and rear axles as evenly on the scale pads, fore and aft, and side to side, as possible. Get back in the driver's seat, and then with a LONG pole, reach up and hit the scale operator call button. When asked for your ICC number, just say "private vehicle." When the operator tells you they have the weight, pull off the scale, park, and go pay for your weight ticket.

You'll have three weights, steer axle, drive axle, and total. If you're doing this with the trailer attached, you'll also have a trailer axle weight. To get the tongue weight, you'd have to drop the trailer off, pull the truck back on the scales and get the weight without the trailer.

There should be a plate on the driver's door jamb with Gross Axle Weight Ratings for the front (steer) and rear (drive) and Gross Vehicle Weight Rating (Total - no trailer). That will tell you how much you have left out of the GVWR for tongue weight, and how much out of the GCWR (in the operators manual, not the door jamb) for total trailer weight.

The actual towing capacity will be the lesser of the tongue weight capacity multiplied by about 10, or the GCWR minus total weight.

Then, as you've discovered, you have to account for the RV/boat manufacturer understating the actual weight of the optioned, wet and loaded vehicle.
--
Moe

[Frank C]

The SUVs are obviously not going to do so while also carrying six adults.

Frank, your opinion is rather depressing. One of the biggest reasons I want a new tow vehicle eventually, is that I DO want to be able to put 6 people and a big load of stuff into an SUV and still be able to tow a Mac. . . .

Sorry to bear bad tidings, but please don't shoot the messenger. Moe's descriptions are completely valid, but let me suggest teh same things in different words.

The tow vehicle's payload must accomodate driver, passengers, cargo and tongue weight. It takes one hundred pounds of tongue weight to tow 1000 lbs. of trailer. So you must be sure to leave about 300 lbs. of spare payload to carry the trailer. The thing that bothers me is that, even when payload is adequate, it sometimes seems the rear suspension is too soft to really control the tongue weight. Since you don't want to push everything to limits, you'd probably want to save 600 to 700 pounds of surplus payload. In my layman's opinion, rear overhang is a culprit here.

If you move 500 pounds of your cargo back to the boat, it means you only need provide 10% (just 50 pounds of payload) for its tongue weight - EUREKA! But unfortunately, we've all seen that the trailer tires provide only enough capacity for the boat and motor - oops! If you really need to haul six adults plus a hefty measure of cargo, choose among:

• 1. Adding tire capacity to the trailer
  2. Or, a 3/4-ton Suburban (which will ride like a horse cart when not towing).
  3. Or maybe a 1/2-ton Silverado Crew Cab (sorry, Dad was strictly a GM guy)

If you really need to haul the boat plus a football team, upgrading the trailer capacity is clearly a cost-effective enhancement.

[Zoran]

Chip said: Would you rather be behind an indequate tow vehicle being driven conservatively or an adequate vehicle driven by a maniac?

Chip this could be very good question with just a small change and if you are asking: Would you rather share the road or be the passenger in/with
1 - an inadequate tow vehicle driven within the limits of that rig by a good driver, or
2 - an adequate vehicle driven by a maniac?
I am for the option one, what is your choice?
If one is using the vehicle to tow once a month for a less than 50 miles and in the same month drive the same vehicle down the busy city roads 1500 miles (driving one of your kids to soccer, other to piano lesson, dropping the Admiral in grocery store in addition to every day work comute) I believe it is inadequate to have full size V8 engine truck. Too uncomfortable, hard to park on many places, waste of gas and bad for the enviroment. For this Odissey is more adequate, and if you are towing as I am 200 - 250 yards within marina with fairly flat ramp than even Civic is adequate. If you are in trade and need V8 extended cab truck for everyday use and buy Odissey for towing than something is wrong with you.
Saying this, for towing out of marina I will borrow a truck from my friend (once or twice a year) since I truly believe that it is not safe to tow with a Civic on the roads. I also truly believe that it is safe to tow on freeway with Chevy Astro, or Odissey doing up to 100km/h on freeway. Many people are doing it for many miles without problems and accidents.
I towed with full size trucks and I am not a fool, but if I have money for purchasing, maintenance and insurance for a tow vehicle that I will use once or not at all weekly for about 8 months here in Vancouver, and once a month for the rest of the year, that will say that I have all mods done in my boat, my house, purchased a apartment on Whistler (I like skiing too), my wife will have all fashion rags she wants (boy are those purses and shoes expensive), our contest HAM radio station wil have separate tower with monobander stacks for each frequency,..., I will have all that money and will not have to go to work... Oh what a wonderfull dream.
And I am repeating again, I do not think either me while I towed with Astro van, or Dimitri with his Odissey are dangerous on the road. I believe we are safe otherwise we will not put our most precious families in those rigs. We are within the limits of those vehicles. Goverment and manufacturers spent lot of money and tested them extensivley to define these limits, and if you are to proof me wrong please try with some credible statistic or study.
Zoran

[craiglaforce]

Zoran,
I was well and truly amazed at your ability to pull a mac up a ramp with a Honda Civic. Maybe you should contact Honda and see if they want to use this in a commercial. You might want to keep in mind that an older, used, large truck or van can be purchased for very little money if you shop around . Might even be cheaper than a new transmission for your Civic. (I don't recall if you have an automatic or manual transmission.)

For me, the reason to go to a real truck (van) for towing had nothing at all to do with engine size or weight limits. It was a matter of keeping the trailer under control at speed. I chose the full sized van because the tow ball is very close to the rear axle and low, the suspension is very stiff and does not oscillate back and forth vigorously at speed when trucks pass. (plus I just like vans). The SUVs I tried would oscillate with the same frequency period as my response time to the trailer swing. The suspension was just too soft and springy with inadequate damping. When a steering correction was made, it would correct back to course, then the stupid springing would overshoot and throw the rig off course in the other direction, recquiring a reverse correction which in conjunction with the spring windup, would build out of control. The result was something like the Tacoma Narrows bridge failure, where just a little wind caused resonant oscillations to build to a point where the bridge flew apart. I'm sure most decent sized SUVs would suffice if the suspension and shocks are upgraded. I'm no expert on suspensions, other than noticing how they behave (or misbehave). I know with US vehicles there are usually several suspension options when new vehicles are purchased so this might explain why some SUV owners have had good experiences while others have not. Mid size vans like a voyager or odessey might be better than an SUV if they have stiffer springs, and carry the hitch ball lower and closer to the axle. Non-US suspensions tend to feel a bit less mushy as well (my opinion) which should be helpful in keeping good control.

Actually, something similar can happen when sailing downwind. The roll induced by overtaking, following seas can interact with helm corrections and result in a rolling motion that it pretty intense and undesirable.



.

[deacm]

Wow, you guys, this has been a great thread to my initial question. I think we could offer a PhD in a correspondence course now on the subject. Thanks !!

Let me throw something else into the equation: Wheel/Tire size. It's been mentioned that being close to the ground is helpful in adding stability. A certain Ford F-150 has 17 inch wheels (and in fact it seems higher off the ground than 'stock' F-150's). Does replacing the 17 inchers with 16 inchers increase stability (as well as increase gas mileage?)

[Moe]

I can't remmeber off-hand exactly what size tires the F150 uses, but it's not just the rim diameter that matters, but also the sidewall height times two for total tire diameter.

(Section Width X Aspect Ratio X 2) + Wheel Diameter = Overall Diameter

Since Section Width is metric, you have to divide it by 25.4 to get inches

Aspect Ratio is used as a decimal fraction of 100, i.e. 0.75 for 75%

If I'm awake enough to do this right, 265/75R16 tires should be about the same overall diameter as 265/70R17 tires. So it may be possible that a 17" wheel option isn't any taller than a 16". Again, I don't know about the F150.

Increasing overall diameter is like raising the gear ratio (lowering it numercially (for example from 3.73:1 to 3.55:1 is going to a "higher" gear ratio)). This will decrease your acceleration and load pulling but will lower the engine speed at any given rpm, which might give better gas mileage.

Increasing the diameter 1" increases the vehicle height half that amount.
--
Moe

[Chip Hindes]

That would depend on a lot of other factors. Exactly what size tires? (both the 17" and the 16" you're considering replacing them with).

In my book, going to smaller wheels/tires as a means of lowering the vehicle is a bad idea.

You could acccomplish the same thing, way cheaper by going to a lower aspect ratio (i.e., 60 series instead of 78, or 50 instead of 60). Even then there are going to be some sacrifices.

You're hinting at the fact that a "stock" F150 comes with 16" wheels, whereas I'm quite certain both 16" and 17" wheels have been factory options for several years.

Assuming however you accomplish it, the new tires have a smaller rolling radius than those they are replacing, the effect is a higher numerical differential ratio. Acceleration should be better, but the engine speed will be higher for a given vehicle speed, and gas mileage is likely to be lower, not higher. You'll screw up your speedometer reading. You'll almost certainly reduce the load capacity of your truck.

If you go the route of smaller wheels, about the cheapest you're going to get away with about $500 for the new wheels, assuming you wait until you need new tires anyway; though I suppose you might save a few bucks on 16 versus 17" tires.

I believe about 98% would consider your proposed move a downgrade, not an upgrade.

[Moe]

Actually, on the F150, 16" rims USED to be optional, then they became standard, and 17" was optional. Now 17" is standard and 18" is optional. Note that as rim diameter increases, aspect ratio generally decreases, keeping overall diameter about the same. This is the new rubber band on a spool look, but it does decrease lateral roll of the tire. OTOH, it makes it more likely that hitting a pothole will dent or crack a rim.

Most F150 tires are passenger car tires (P-metric) and you'll do well for towing to replace them with light truck tires (LT) and the higher the load range, the stiffer the sidewall (for example, Load Range D, or at least C on an F150).

A small change to a SMALLER overall diameter does a lot of small things. As Chip said, it's like lowering (raising numerically) the axle ratio, so a smaller diameter gives you a bit more pulling power, at the expense of slightly higher rpm at any given speed. This may reduce your non-towing highway mileage slightly, but may even improve your towing and around town mileage.

It WILL decrease your vehicle's actual speed and miles travel compared to what the speedometer and odometer show, and can throw your ABS off, until you have the ABS computer reprogrammed for the new tire diameter.

It will lower the vehicle slightly, but the overall effect on stability depends on more than that. A lower vehicle means you have less ground clearance, the hitch will be a little lower, and you won't be able to back _quite_ as far in on a ramp before getting the trailer coupler wet.

I'm sure there's more I've forgotten to post, but these are a few more things.

--
Moe

[Chip Hindes]

Most F150 tires are passenger car tires (P-metric) and you'll do well for towing to replace them with light truck tires (LT) and the higher the load range, the stiffer the sidewall (for example, Load Range D, or at least C on an F150).

Just a warning, this is not necessarily a cheap nor easy upgrade.
When I tried to do this on my Expedition, I was told my stock wheels weren't rated for the higher pressure (50 psi for the LT vs 35 psi for the P)

I'm usually pretty cynical when it comes to such claims as I've found in general many tire people are incredibly ignorant of their product. But since they could have sold me a more expensive LT tire if they'd unquestioningly done what I asked, I assumed they had no reason to get this wrong. It occurs to me, though, they were just trying to get me to buy new wheels as well. That would be more like most tire salesmen.

[Robert]

If you are modifying to get more stability for towing and have already done the easy inexpensive stuff like better shocks and progressive springs, and have come down the adjusting your tire size (instead of just getting a quality tire rated for good handling), then consider going wider by getting rims with more offset than stock. If your wheelwells will allow a wider track (most will), there are available aftermarket rims with extra offset, presumably, the wider apart the tires the harder to flip a vehicle, the more stable in turms and the less sway etc...
..
IMHO, lowering the vehicle by smaller tires or a low rider kit will make it unsuitable for towing. Lower profile tires of the same width as stock have lower load ratings, and the low profile tires do not protect your rims as well in case you hit a pot hole or curb.
..
Just the other day, I hit a very bad pot hole. I had no damage, but a high end BMW with tall rims and very low profile tires had pulled over, I assume due to damage from lack of protection.
..
Hit a pot hole with the extra force of the trailer behind you with low profile tires.... I would not want to be in the tow vehicle at that event.

[Dimitri-2000X-Tampa]

Your story reminds me of an incident that happened last year when I was towing my Mac down to Gulfport. I was on I-275 in St Pete probably doing about 65 in a rather congested part of the Interstate. My cell phone rang so I looked down for a moment to answer it. As soon as I looked back up, the car in front of me had just done an evasive maneuver to avoid some debris in the road, kinda looked like some half rotten 4X4 or similar pieces of wood. It was too late and too dangerous to try to swerve much as I was in heavy traffic and the debris was right on me. I missed it with my left front wheel but clipped it with my rear wheel. About then, I looked in the rear view mirror and it reminded me of that scene from madmax when the motorcycle gets run over by the tanker truck. The left trailer wheel hit the wood and the trailer jumped up some as it hit. I didn't panic and the rig stayed well under control. The wood kind of blew apart at that point and I was sure I must have damaged something. My wife was following behind me in the other car and she managed to swerve and avoid the debris.

I pulled over shortly after that and to my amazement, no damage to the van, trailer, or stock titan bias ply tires. A few months later, I did the tires in by gouging the sidewall of one of them on a bolt sticking out of a fence post though.