Weight on rear bumper hitch

I have a 2008 2720 TM that I recently purchased to replace a 2008 Aliner Expedition. I frequently use the TM to go to various auto races, and like to take a small scale motorcycle to use as pit bike. The stated weight on the motorcycle is 140 lbs.

I have examined the rear bumper and hitch assembly on the TM and find that it appears on par with the assembly on the rear of the Aliner. I had no problems at all with the extra weight on the Aliner, and am asking if anyone has any experience with hauling moderate amounts of weight on the rear of a TM.

Any experience, good or bad, would be helpful. I am aware that the rear hitch is labelled saying 100lbs. max dead weight.

I ordered the trailmanor bike hitch receiver and installed it in the garage a couple of years ago. I have my trailmanor backed into the garage now so I can't check the size of the attachment plate and bolt diameters so I will try and summarize from memory and give you some advice.

When I got the bike receiver and it said maximum load 100 lb I was quite surprised since it seemed very low. Anyway having used it for many times, with sometimes putting 3 bikes on my 4 bike carrier (say 130 lbs+ my 30 lb bike carrier = total 160 lbs)) with no problems. The bike hitch receiver attaches to the C-channel frame of the trailmanor. The 2 inch square box sections of the bike hitch receiver are very strong steel box sections going from side to side and are welded to a relatively thin plate (I would say no more than and perhaps less than 1/8 inch). It connects to the C-Channel trailer frame with a couple of gavanized bolts which from memory were between 3 and 4/8 inch in diameter and spaced at about 4 inches from top to bottom. Even a 3/8 inch diameter bolt should have a shear strength of 3000 lbs, so the weak point could be the thin plate of the bike receiver plate in bearing against the bolt. The mechanics of putting a motor bike out with its centre of gravity say about 20 inches back from the centreline of the bike hitch receiver attachment is that it will create a moment of 140 lbs plus the carrier weight (say 200 lb) times about 20 Inches that must be resisted by 2 bolts (one each side) over a moment arm of 4 inches plus the vertical load of the bike itself. This would equate to a static load of about 500 to 600 lbs on the bolt on each side. If you consider the dynamic effect of going over speed bumps and pot holes (say with an impact factor of 3) it might be possible to generate 1800 lbs shear in the bolts which should be okay. I can't remember the exact thickness of the bike receiver thin plate but I would guess that the weak point would be the bolt bearing capacity (strength of plate bearing against the bolt) against the bike receiver hitch plate. A simple solution to strengthen this aspect would be to install larger bolts, enlarge the holes in the thin plate and drill larger holes in the C-channel which you have to drill yourself anyway. Using larger bolts with helical spring lock washers and large plate washers and making the larger bolts tight should increase the bearing capacity of the thin plate.

Of course another way to load check it to see if the 200 lb bike and carrier is okay, is to get a couple of 200 lb men to simultaneously jump up and down in unison on the carrier (say 400 lbs x 1.5 load factor=600 lbs) and if that does not damage the bike receiver attachment then you are probably okay.

Two comments, leaving opinions to others.

Adding weight at the rear of the trailer changes the tongue weight at the front, and at some point the handling. Where that weight becomes an issue is unknown to me.

Exceeding rated weights of anything can void warranties, make insurance claims difficult and expose a person to liability if an incident or injury occurs from failure of overloaded parts. Using an overloaded receiver hitch makes you a test pilot.

Well put, Mr. P. There was a very substantial verdict in central Illinois several years ago based in part, if I recall, on an overloaded hitch and failure to cross tow chains under the trailer tounge. Our local independent trailer store has the newspaper report of that case on the bulletin board. - camp2canoe

I think it's also important to understand that the bike may weigh 140 lbs static, but whenever the trailer would bounce (bumps, railroad tracks, etc) this 140 lbs can be multiplied several times. Understand this, you can theorize that the max load of 100 x 3(?) = 300 lbs bounce/shock load, while at a static load of 140, the bike would become 420 lb bounce/shock load. Then multiply this by the number of bumps you'll hit, and you can imagine the number of overloaded shock loads that the hitch/receiver will be seeing over time.
I would assume due to this, there is a safety factor build in to the "max 100 lbs", thus we all feel it's so low. While 40 lbs doesn't seem like a lot, it's actually 40% over load, which is quite a lot.
IMHO, I would not do it.
It's simply not worth the risk of sending a 150 lb projectile down the Interstate towards another vehicle.

It would probably work well on a smooth Interstate freeway.

Let me know when you find one.

[Mr. Adventure]

Originally Posted by MisterP

Two comments, leaving opinions to others.

Adding weight at the rear of the trailer changes the tongue weight at the front, and at some point the handling. Where that weight becomes an issue is unknown to me.

Exceeding rated weights of anything can void warranties, make insurance claims difficult and expose a person to liability if an incident or injury occurs from failure of overloaded parts. Using an overloaded receiver hitch makes you a test pilot.

Void warranties = Yes.

Make insurance claims difficult = No.
All at-fault accident claims are paid by your insurance company because of your personal negligence. I've never been able to find a single RV case where somebody made an issue of something like this (If you Google "Trailer Accident", for example, it's mostly about poorly attached trailers that become disconnected and injuring someone). Most policies cover you pretty well for even the most stupid accidents, but quote me a piece of a policy that mentions the mfr ratings of something like a trailer hitch, and I will go back and correct everything I've posted on this subject.

Liability because of exceeding mfr's recommendations = No.
MFR's ratings are recommendations and not laws. But, quote me a piece of a state motor vehicle code that mentions a manufacturer's load rating and I will cheerfully stand corrected. So far, the only exception I've found is in California where it is against the law for a tire to be loaded higher than the number on the sidewall.

Test Pilot = Yes.

^^ I was talking about civil liability not motor vehicle code. If my overloaded bike rack leaves my trailer and hurts someone, a good attorney will ask for an inspection of the equipment and its rated loads. I have civil liability if I have exceeded the manufacturer's ratings.

We will have to agree to disagree on this one.

I agree with you on the insurance, I should have left that out of the statement. That is the whole point of liability insurance. An interesting topic for another time is whether insurance companies can and have reduced their exposure due to negligence of a driver. But that is a complex topic and not related to this thread.

On RV.net about 4 years ago someone posted a story that they had experienced regarding accidents and trailer weights.

Driver towing a travel trailer (not a TM) loses control in a turn. Nasty things happen to the trailer. Someone is killed in the accident.

Author of the story I read asked the troopers why they were so careful about picking up every piece.

Trooper explains that if it was overweight (without defining what overweight is) then the driver would be charged with felony manslaughter.

Author of the story claimed he was driving his vehicle behind the trailer. Towing the trailer were his parents and his son.

Grandma was killed.

This may be a yarn or an urban legend being repeated.

I, for one, would be very interested in knowing how real this could be. As I recall it was in Ohio.

If true, I do not think this fits within DMV code.

My older brother is at some risk. I am certain that the weight of his truck and 5th wheel trailer exceeds the magic number (12,500 I think) that requires him to have the California endorsement on his license to tow a trailer between 12,500 and 15,000. He does not have that endorsement.

I do not have that endorsement. Fortunately, as heavy as I load up my TM, 4,100 pounds is way less than 12,500.

I do know that we had a rash of debris (ladders, saw horses, etc) on the Interstates caused by contractors not loading their pu's properly. Several serious accidents were caused and I believe a couple of deaths. This prompted the State Police to issue warnings via local tv to such contractors that the police would be patrolling and ticketing trucks with unsafe loads. Accidents/deaths caused by these kinds of incidents were going to be prosecuted to the full extend of the law, etc.