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Old 11-06-2012, 10:48 AM   #21
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Originally Posted by Filthy Beast View Post
mewildman, it seems that sometimes it is hard to get a straight answer to a question. I personally don't have a real understanding of the length issue of the TT as I have only pulled the fifth wheel. maybe someone will address the length thing for you.
There is no "official" straight answer to the question of bumper pull trailer length vs. tow vehicle wheelbase.

It is generally thought that a longer wheelbased tow vehicle will handle a long trailer better. The longer wheelbase helps to keep the trailer from pushing the tow vehicle around as much.

There are many more parts of the equation. Weights (both trailer and TV), WDHs, anti sway systems, etc.

There was a popular chart published on a website a number of years ago, but that site had to be close down because of copy right complaints from another site. There was no down and out research behind the chart that I know of. It was the "suggested" tow chart of the operators of the site, but it was widely recognized around the bumper pull community.

110" 20' ******* 150" 30'
114" 21' ******* 154" 31'
118" 22' ******* 158" 32'
122" 23' ******* 162" 33'
126" 24' ******* 166" 34'
130" 25' ******* 170" 35'
134" 26' ******* 174" 36'
138" 27' ******* 178" 37'
142" 28' ******* 182" 38'
146" 29' ******* 186" 39'

The 1st figure would be the wheel base in inches, and the 2nd was the suggested overall maximum length of a conventional, upright, bumper pull trailer in feet. There is an equation floating around that closely matches the chart: The tow vehicle wheelbase in inches divided by 5 should be the maximum overall length of conventional, upright, bumper pull trailer in feet. These are no hard and fast rules, but are just guidelines some people familiar with bumper pull trailers came up with. Does going 6" over the guideline make that much difference ?? Of course not. but what about 6'....that would be questionable in my book. Where is the cutoff ??

This was posted earlier:
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Originally Posted by ironj View Post
Its really not that black and white......think of it more as a gradient from safe to absolutely not......

Given, what you tow, how far you tow, where you tow, and your experience, where do you feel that line is?....

Being at max capacity on a short wheelbase vehicle leaves you with very little saftey margin, but some are perfectly happy to ride that line and tow that way....it doesnt mean you are overloaded....if you are confident in your driving and understand the limitations and extra attention that needs to be given to the vehicle and conditons you may face, then go for it.....
I think that is a pretty good summary.

Would I tow my 28' trailer with my 93" wheelbase Jeep Wrangler...... absolutely not !! I towed a very small popup with the Jeep, and even that was a bit much in my book.

After everyone's input here, the OP is the only 1 that can sort out all of the information and make the decision whether his tow vehicle can tow safely tow his trailer.
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Old 11-06-2012, 10:51 AM   #22
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Again... run the #s yourself ... a good exercise

Tow Vehicle Sizing
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Old 11-06-2012, 11:10 AM   #23
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I will be happy to be corrected if wrong, but I believe the issue of wheelbase is a simple physics issue. How long is the fulcrum. The further the front wheels are from the rear wheels the more force the wheels apply left and right, controlling the track of the trailer. Basically, the TV is a lever, the rear wheels are a fulcrum point applying left and right force to the TT.

As a tractor trailer passes, or a crosswind blows, the TV needs to counteract the effect on the TT to maintain lane. The longer wheelbase means the more counter-force that is already in place, so less of a reaction is required of the driver.
The more you have to work to get to your destination dealing with these issues, the less energy you may have for enjoying the destination.
Once at the destination, it is ok to have a short wheel base for parking, but that is a small amount of time, relative to the trip, that you will be enjoying the benefit.

In the event of an emergency (sudden lane changes in front of you, etc.), you will have less force available to work with controlling the rig, so safety is a real factor.

So... I guess I would just be confirming your choice to change vehicles. Until then, make sure you WDH is set up to assure your front wheels are as effective as possible. A visit to the CAT scale is probably a good idea if you have not already been.

I really do agree with the other posters. Mid-size SUVs are a compromise for better mileage, but mean a lower safety margin.
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Old 11-06-2012, 12:00 PM   #24
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Quote:
Originally Posted by Arefbee View Post
I will be happy to be corrected if wrong, but I believe the issue of wheelbase is a simple physics issue. How long is the fulcrum. The further the front wheels are from the rear wheels the more force the wheels apply left and right, controlling the track of the trailer. Basically, the TV is a lever, the rear wheels are a fulcrum point applying left and right force to the TT.

As a tractor trailer passes, or a crosswind blows, the TV needs to counteract the effect on the TT to maintain lane. The longer wheelbase means the more counter-force that is already in place, so less of a reaction is required of the driver.
The more you have to work to get to your destination dealing with these issues, the less energy you may have for enjoying the destination.
Once at the destination, it is ok to have a short wheel base for parking, but that is a small amount of time, relative to the trip, that you will be enjoying the benefit.

In the event of an emergency (sudden lane changes in front of you, etc.), you will have less force available to work with controlling the rig, so safety is a real factor.

So... I guess I would just be confirming your choice to change vehicles. Until then, make sure you WDH is set up to assure your front wheels are as effective as possible. A visit to the CAT scale is probably a good idea if you have not already been.

I really do agree with the other posters. Mid-size SUVs are a compromise for better mileage, but mean a lower safety margin.

This is a good post. The amount of leverage the travel trailer has on the counteracting wheel base is determined by the rear overhang (distance from the rear axle to the pivot point).

Wheel base can be shorter if the pivot point is not sitting at a leverage point behind the rear axle. Take a look at the wheel base of the next semi-truck in relation to the trailer it is pulling.


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Old 11-06-2012, 01:25 PM   #25
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Originally Posted by Sean Woodruff View Post
Take a look at the wheel base of the next semi-truck in relation to the trailer it is pulling.
With a 113" wheelbased vehicle pulling a 27.5' travel trailer, the tow vehicle is about 34% of the total trailer length.

A typical twin screw conventional road tractor with a medium sized sleeper has about a 230" wheelbase. Pulling the maximum legal limit 53' trailer, that the tractor wheelbase is about 36% of the total trailer length.

Plus, the hitch weight of the semi trailer is directly over the back wheels, not extended way behind the wheels. Plus (again), the road tractor is made for that type of pulling.

Those road tractors may look small in relation to the trailer, but they actually have a very long wheelbase.
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Old 11-06-2012, 01:39 PM   #26
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Quote:
Originally Posted by mtnguy View Post
With a 113" wheelbased vehicle pulling a 27.5' travel trailer, the tow vehicle is about 34% of the total trailer length.

A typical twin screw conventional road tractor with a medium sized sleeper has about a 230" wheelbase. Pulling the maximum legal limit 53' trailer, that the tractor wheelbase is about 36% of the total trailer length.

Plus, the hitch weight of the semi trailer is directly over the back wheels, not extended way behind the wheels. Plus (again), the road tractor is made for that type of pulling.

Those road tractors may look small in relation to the trailer, but they actually have a very long wheelbase.

That 34% wouldn't fit in the wheel base to length chart above.
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Old 11-06-2012, 03:21 PM   #27
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That 34% wouldn't fit in the wheel base to length chart above.
Agreed. That chart goes from about 46% for the 20' trailers to about 40% for the 39' trailer.
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Old 11-06-2012, 08:25 PM   #28
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My liberty is shorter than listed. I guess the length police will be after me, too.

But I guess someone should tell UPS that a single screw day cab is too short to pull twin 45 foot trailers.
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Old 11-06-2012, 08:44 PM   #29
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My liberty is shorter than listed. I guess the length police will be after me, too.

But I guess someone should tell UPS that a single screw day cab is too short to pull twin 45 foot trailers.
They should and then get on the railroads that have 3 engines(150') pulling a mile (5280') of freight cars.
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Old 11-06-2012, 08:59 PM   #30
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That is in a state where it's legal to double tow with a fiver and most likely those are both empties being relocated. BTW, I'll stir the pot here. What about an HD pickup say a F350 or F450 screw with a 30'+ fiver and say a 15' trailer off the back of the fiver?
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