Travel Trailer Suspension Adequacy (or Inadequacy)

[RUSSELL5000]

I have a 2012 2500 crew cab ST w/ 4WD; rear axle is 3. 73 ratio, automatic transmission - bought new.



I have a 1995 Jayco Eagle Series 304 BH travel trailer - it is a tandem axle pull-type trailer - new to me. If I have a correct understanding from my reading it is rated:



GVWR = 7,800 lbs. I believe this is the Gross Vehicle Weight Rating, which means that this is the maximum amount the trailer and contents is rated for; that is, this is the highest loaded weight allowed.



GAWR front = 3,500 lbs; same for GAWR rear. I believe this is the Gross Axle Weight Rating, which is the weight an individual axle is designed to carry.

The axle tubes measure three inches in diameter and are slightly bowed up - that is, the distance from the ground to the bottom of the axles is greater in the middle of the axle than at the end of the axle. There is three includes of distance from the axle top to the frame. It appears, as best I could measure, that the center of the axles is four inches lower than the center of the wheel spindle. I believe all of this so far means that there are two 3,500 lb four-inch drop axles which are cambered (if I understand all this correctly).



The suspension is the leaf spring type - each end of the springs has an eye, and there is an equalizer in the middle. The end bolts are ordinary nuts and bolts - no grease fittings. There are three leaves in each spring.



It has drum brakes that are electrically activated - a magnet setup. The drums are ten inches in diameter.



It has 15" by 5" wheels with ST205/75 R15 tires with load range C stamped on them. The wheels have five bolt holes.







OK - it seems to me the suspension is right at the border of inadequate - actually, I don't understand how the axles can be rated such that they will carry 7,000 pounds, the tires rated such that they will carry 7,200 pounds, and the trailer saying that it can be loaded up to 7,800 pounds. How is that safe - I don't even see how the arithmetic works. ???



This returns me to my original thinking: since the suspension and braking is all 18 years old, and complete assemblies appear to be readily available, why not replace the entire axle assemblies with 5,200 lb rated axles. This would have four leaves per spring. All the brake hardware would be new as well. I could also improve with steel bushings in the spring eyes as well as the bolts with the grease fittings for the spring eyes. To my mind this suspension would be safely capable of carrying the load - it seems simple to me that if you are only asking 75%-80% of the capability of the hardware that you should be in good shape (in contrast to asking somewhat over 100% of the capability of the hardware).



Finally, I think it would make sense to go to a 225/75 R15 load range D tire up from a 205/75 R15 load range C. If I understand it correctly I would then also be at 75%-80% of the rated capability of the tire - again, rather than a little over 100% of the rated capability.



In a nutshell, it seems to me that the suspension and tires are just barely adequate for the job, and that if I want to roll across the country with no worries I should have a suspension that is not being pushed to its limit (or a little past its limit).



My perspective on this is pretty simple - I expect that my wife, two boys, and two dogs will take the rig and go somewhere and I'll catch up with them on the weekend - then they will take the rig and come back or go somewhere else for me to catch up to again (I get to be at work - how it goes, I guess). So, my goal is that the rig is absolutely safe. There is going to be a whole lot more of value in that rig than the cash in my wallet.





Thoughts? Am I making sense on any of this?





This is a follow-up to my original thread which raised a number of issues. I am still reading and educating myself on1) LT versus ST tires for trailers, (2) weight distributing hitches, (3) trailer anti-sway components for hitches, and (4) trailer brake controller - specifically MaxBrake.





P. S. - after looking into all this in more detail I am even happier with my choice of truck than before. If I round GVWR to 8,000 lbs, then it seems to me I will be working with the truck at around 75% - 80% of its rated towing capability.



Thanks to all for your earlier responses, as well as now.



Russell

 

[EricBu12]

Russell.
As far as the truck is concerned, no problemo. A trailer that light will not have too much problems on the truck. Dont need a WD hitch. . maybe look at a friction slider anti sway device. .
The GVWR includes the weight on the hitch which is around 700-780# so for GVW, the 3500 axle is about right. . the tires on the other hand are light. . best to get a D tire. l on my 5th, I used BF Goodrich Commercial T/A. Now my tires are 16" E but I think they make a 15 D.
Weighing the trailer empty with water in and propane, that weight to GVWR is what you can put in the trailer.
If you replace the axles with heavier ones, it wil in sense, raise the carry capability. I don't think you will need to do that. . just get better tires.
I had a 28' desert fox toyhauler with my old 2500 2001. It was 12000# gvw and my old truck did great. Just make sure none of the components are overloaded and you will be fine.

 

[jelag]

Remember that the trailer has some tongue weight... the rating on all axles does not include the weight of the axle, tires, wheels and suspension... so lets say that there is 10-12% of tongue weight... that's about 800 lbs, and that each axle with it's hardware weighs 350 lbs... 700+800=1500 less the max of the trailer... . 7800 - 1500 = 6300, which sounds about right for the trailer... If you look at a Dexter Axle catalog you'll find most of what I've shared above. .

Even with the age of the trailer and axles... I'd be sure the brakes and bearing were in good shape... if the shackle bolts and bushing are dry I'd lube them... if their plastic I'd replace them with brass bushing and lube-able bolts. .

I'd change out the tires if they are trailer only tires... I'd look at the serial # of the tires and track back to how old they were... and I'll get some comments on this... if they are commercial tires... and have no sidewall cracking down to the cord material... and have been aired up over the years. . I'd run them... if they were over 7-8 years old I'd consider replacing them... I own several work trailers with 10 year old commercial tires, no side wall cracks and we use that trailer all the time loaded...

I'm sure as soon as I post this... I'll think of more to write... but these are my first thoughts... hope it helps. .

 

[RUSSELL5000]

Jim and EricBu12:

Thanks for the insight on the capacities.

I found the Dexter catalog on-line last night - have not read it - I will this weekend.

Based on what you described above, I can see that the axles would be about right then. I have looked at costs and I think a complete replacement of bearings and brake components is already decided.

I may just replace the springs, shackles, equalizers, bushings and add the lube-able bolts. The costs of those parts seems reasonable. Also, unless very badly worn (loose shackles), it seems to me that you do all the work to take apart you and inspect carefully you are almost at the cost anyhow.

The tires are quite old - the trailer was parked for years - so am going to replace.

I do see 225/75R15 load range D tires commonly available - there is even a load range E. I guess this will move into the LT versus ST question.

Thanks for the input - more to think on!

Russell

 

[HBarlow]

As explained, the OEM axle assemblies are adequate but only adequate. The tires are probably not. Complete new axle assemblies are not expensive and if new ones would give you peace of mind why not? In any case it is a good idea to replace the old and well used brakes with new complete loaded brake backing plates which can be purchased from lots of trailer supply stores like Southwest Wheel in Texas, Redneck in MO and other states, and more.

15" trailer tires, even Goodyear Marathons in LRD, are well known for tire failures. Many who pull their trailers a lot and don't want repeated tire failures replace the wheels and tires with 16" wheels and LT tires. That will eliminate tire failures. The problem is 16" wheels are available in 6 lug or 8 lug configurations so that would be another reason to convert to 5200 lb. axles which have 6 lugs.

 

[NIsaacs]

the trailer was parked for years



Russell

This might answer some questions, the suspension, brakes and wheel bearings might be fine (low milage). If they are, it would be hard to improve them by replacement. A good cleaning and repack of the bearings (include seals) inspection of all brake and suspension components, repair/replace as needed.



I would not be afraid of a good quality D or E rated 15" tire in the size/capacity that will give a good weight reserve cushion.



I am also not in favor of greaseable suspension components, they just collect dirt/road debris. The oem works and when replacement time comes it will only cost a few $.



Nick

 

[crispyboy]

Your asking for opinions so here we go!
Suspension: As stated by others what you have was engineered to do the job up to the specified weight. The question now is what shape is it in versus what would it cost to upgrade to a new assembly. It may be worth your while if you plan on keeping this trailer for awhile to do this. If you do this I would upgrade to the 12 x 2 brake. Put the cost of parts versus replacement down on paper and make the decision. The other factor would be if you can do the work yourself or will it be done by others.

Tires: Is there room in the wheel well to upgrade to a better tire? A 225/75/15 D rated tire is what I would use at a minimum. I have been lucky with ST tires but from everything I read I will opt for the Yokahama RY215 or Continental Vanco 2 when I change out in 2 years from now. There should be a 4 digit date stamp on sidewall of the current tires.

Hitch: In your original post you said that your family may be driving the rig to the destination and you will be meeting them. It seems that you have a CONCERN ABOUT SAFETY. I tow a travel trailer approximately the same size and weight and I feel from my experience that a WEIGHT DISTRIBUTION and ANTI-SWAY hitch are absolutely necessary if your going to be driving several hundred or several thousand miles. If you were just going to the local camping spot 20 miles away you could probably get by without it. I have towed this weight with and without a hitch and I would spend the money on a good hitch to keep my family and investment of the truck and trailer safe. When you go across the country you can encounter poor roads, cross winds, poor drivers etc... ... The idea behind the weight distribution is to put the original weight back on the front axle to restore the steering geometry, braking abilities plus the added benefit of a good ride. This also keeps the truck and trailer from porpoising or wallowing about on the road. Don't waste your money on air bags. They are only needed for towing fifth wheels or goosenecks. The anti-sway part is necessary for the cross winds, passing semi's, winds from a thunderstorm, swerving to go around sudden debris or pothole in the road etc... It keeps things straight especially when you encounter something unexpected.

I WOULD NOT BUY THIS FRICTION BAR. It might be ok for a pop-up size trailer but not a full size travel trailer.

At a minimum I would buy the Reese Dual Cam or Equalizer hitch. If you get the Reese dual cam go with 600 lb bars since your tongue weight is probably about 800 lbs. Anything more will give you a rough ride and negate the anti-sway aspects of the hitch. Go to a scale and see what the trailer axle and tongue weight are. This will also help with your selection of suspension.

Equalizer hitch

 

[crispyboy]

Your asking for opinions so here we go!

Suspension: As stated by others what you have was engineered to do the job up to the specified weight. The question now is what shape is it in versus what would it cost to upgrade to a new assembly. It may be worth your while if you plan on keeping this trailer for awhile to do this. If you do this I would upgrade to the 12 x 2 brake. Put the cost of parts versus replacement down on paper and make the decision. The other factor would be if you can do the work yourself or will it be done by others.



Tires: Is there room in the wheel well to upgrade to a better tire? A 225/75/15 D rated tire is what I would use at a minimum. I have been lucky with ST tires but from everything I read I will opt for the Yokahama RY215 or Continental Vanco 2 when I change out in 2 years from now. There should be a 4 digit date stamp on sidewall of the current tires.



Hitch: In your original post you said that your family may be driving the rig to the destination and you will be meeting them. It seems that you have a CONCERN ABOUT SAFETY. I tow a travel trailer approximately the same size and weight and I feel from my experience that a WEIGHT DISTRIBUTION and ANTI-SWAY hitch are absolutely necessary if your going to be driving several hundred or several thousand miles. If you were just going to the local camping spot 20 miles away you could probably get by without it. I have towed this weight with and without a hitch and I would spend the money on a good hitch to keep my family and investment of the truck and trailer safe. When you go across the country you can encounter poor roads, cross winds, poor drivers etc... ... The idea behind the weight distribution is to put the original weight back on the front axle to restore the steering geometry, braking abilities plus the added benefit of a good ride. This also keeps the truck and trailer from porpoising or wallowing about on the road. Don't waste your money on air bags. They are only needed for towing fifth wheels or goosenecks. The anti-sway part is necessary for the cross winds, passing semi's, winds from a thunderstorm, swerving to go around sudden debris or pothole in the road etc... It keeps things straight especially when you encounter something unexpected.



I WOULD NOT BUY THIS FRICTION BAR. It might be ok for a pop-up size trailer but not a full size travel trailer.

View attachment 85088



At a minimum I would buy the Reese Dual Cam or Equalizer hitch. If you get the Reese dual cam go with 600 lb bars since your tongue weight is probably about 800 lbs. Anything more will give you a rough ride and negate the anti-sway aspects of the hitch. Go to a scale and see what the trailer axle and tongue weight are. This will also help with your selection of suspension.

View attachment 85089



Equalizer hitch



View attachment 85090

 

[Bob4x4]

A Ed hitch is a must! The oem hitch is only rated for 500lb max tw without one and jumps to 1000lbs with a wd hitch

 

[HBarlow]

Technically a wd hitch should be used but they are not required by DOT and commercial transporters never use them. I pulled conventional travel trailers hundreds of thousands of miles and never used one on Ram duallies.

 

[TLane]

Kudos to you for looking into this - most people hook up to the trailer and drive off with no idea what the weights are.

Before you believe too much about what the sticker says, load your trailer up and take it somewhere to be weighed. I've weighed mine a couple of times at truck weigh stations for free, but of course I stayed hooked up and got the front truck axle, rear truck axle, and both trailer axles weighed. You can take it to the scale that's available at many truck stops where you can unhook and get the total trailer weight, they usually charge a small fee. Some feed stores also have scales that would be suitable. You should also get (or borrow) a tongue weight scale so you can measure that separately. RV manufacturers are notorious for under estimating the actual weight of the trailer. Once you have that, you have a better idea what you need for tires, axles, etc.

 

[Bob4x4]

Technically a wd hitch should be used but they are not required by DOT and commercial transporters never use them. I pulled conventional travel trailers hundreds of thousands of miles and never used one on Ram duallies.

And we see damaged hitches from being used out of spec... ... no big deal till the tongue hits the ground smh

 

[AH64ID]

I have pulled several campers with my SRW 3500 and sway has never been a concern even towing with just a standard hitch. I like the WD setup for the effect on steering, ride, braking, and headlights.

While you can setup a WD hitch without airbags, adding airbags is a great idea. The airbags reduce sway, bounce, and account for anything you put in the bed. They certainly are not just for 5er or gooseneck setups.

 

[NIsaacs]

A Ed hitch is a must! The oem hitch is only rated for 500lb max tw without one and jumps to 1000lbs with a wd hitch

I always figured that weight rating was free advertising for the hitch manufacturer to sell W/D hitches. They will pack 1000# forever and a day without one. I have seen them damaged but not by an 8,000# travel trailer. If you add a pintle hitch adapter (adds a foot in length) and hitch up an equipment trailer that should be behind a dump truck... .



Nick

 

[Bob4x4]

I have customers pulling tts that have damaged them as well as horse haulers 4 horse trailers. engineering is not as much guess work as some rednecks like to think

 

[Joseph Donnelly]

The axle tubes bow up in the center to give some camber to the wheels; it is normal. It will tow better with Dexter torsion axles.

 

[Terry Jay]

Trailer World, where axles and tires are stressed at 100% all the time.

Got a 15,000# 5th, the tires and axles were rated for 12,000#, the balance was supposed to be on the hitch. Upgraded to 17. 5" tires with nearly a 20,000# capacity, replaced the Lippert axles with the Mor-Ryde IS rubber suspension independent trailing arm suspension, and added hydraulic brakes.

The tires and wheels are now around 60% of capacity. the tires no longer flex significantly on sharp reverse parking and are significantly less likely to be a problem.

It is all a matter of how far and how often you tow. We go at least to and from Alaska every year, call it around 6,000 miles, maybe less. If you tow it out to the lake 50 miles away and leave it for the summer, you may have different issues and experience. It is all in how you use it.

 

[RUSSELL5000]

First, thanks to those who posted - lots of food for thought - have read a bunch - still learning.



I am not an engineer, nor is my line of work mechanical. I have always been conservative regarding mechanical things for this reason. My general approach has always been to try and understand what the capability of a mechanical device is and then use it at around 80% of the capability. I got more than that even with the 2012 Ram 2500 in my case, but there is also a certain degree of enjoyment in driving a truck with a Cummins - my wife would add that the difference between a man and a boy is the size of the toy.



My trailer suspension is not in line with my approach - it is basically right about at its stated capability.



The biggest issue is the tires. This may be addressed with load range D tires. But, I read a ton of threads dealing with problems with trailer tires (ST tires). I can't even tell if anyone makes a good ST tire from all the threads I have read.



My thinking is to upgrade to 6,000 lb axles in order to accomplish two things: (1) the larger axles offer the opportunity to go to a 8 on 6. 5 lug pattern wheel which opens up the possibility for 16 inch LT rated tires, and (2) the larger axles offer 12 inch brake drums rather than 10 inch brake drums. A real concern I have with this approach is how to get this to fit in the wheel wells. The current ST205/75R15C tires are 27. 3 inches in diameter - an LT235/80R16D tire is 30. 5 inches in diameter. There is six inches between the tires now (with the 15 inch wheels) - there is three inches to the fender both front and back and three inches upward to the trailer body. It seems to me all these distances would be decreased by one-half with the 16 inch tires - would all this fit in the wheel well?



If I upgraded to 5,200 lb axles I would still have the 10 inch brake drums as well as a fifteen inch tire - but with a 6 on 5. 5 lug pattern. I note there are ST225/75R15E tires rated at 2,800 pounds and are less than one inch greater in diameter. I think these would fit in the wheel well with the addition of a fourth leaf spring. This would get to the 80% of capability. I have not seen any fifteen inch LT tires. And, my concern with ST rated tires remains.



So, I am still a little confused on the suspension. Does anyone know if a good 15 inch ST tire exists or whether a good 15 inch LT tire exists?





I will go with a weight distributing hitch with sway control. I can't really tell from commentary on the posts and in the reading I have done whether this is required - but, I can see no downside to it - I canlt see how it can be anything but beneficial even if not really required. The Hensley products are extremely expensive - was thinking of going with the Equalizer hitch. My trailer is not all that big, and it seems like it would be easy to use in practice. Does anyone see anything wrong in this approach to hitch?



So - trying to firm up a plan - like everything it seems there are pros and cons - welcome any other insights.



Kevin

 

[NIsaacs]

The 5200 lb axles use the standard 12x2 brakes, 15" or 16" wheels with 6 on 5. 5 are available. I would just replace the springs with a little more capacity rather than adding a leaf. They are only about $30 for 1. 75 X 4 or 5 leaf, 2500-3000 lb capacity.

Nick

 

[HBarlow]

First, thanks to those who posted - lots of food for thought - have read a bunch - still learning.

I am not an engineer, nor is my line of work mechanical. I have always been conservative regarding mechanical things for this reason. My general approach has always been to try and understand what the capability of a mechanical device is and then use it at around 80% of the capability. I got more than that even with the 2012 Ram 2500 in my case, but there is also a certain degree of enjoyment in driving a truck with a Cummins - my wife would add that the difference between a man and a boy is the size of the toy.

My trailer suspension is not in line with my approach - it is basically right about at its stated capability.

The biggest issue is the tires. This may be addressed with load range D tires. But, I read a ton of threads dealing with problems with trailer tires (ST tires). I can't even tell if anyone makes a good ST tire from all the threads I have read.

My thinking is to upgrade to 6,000 lb axles in order to accomplish two things: (1) the larger axles offer the opportunity to go to a 8 on 6. 5 lug pattern wheel which opens up the possibility for 16 inch LT rated tires, and (2) the larger axles offer 12 inch brake drums rather than 10 inch brake drums. A real concern I have with this approach is how to get this to fit in the wheel wells. The current ST205/75R15C tires are 27. 3 inches in diameter - an LT235/80R16D tire is 30. 5 inches in diameter. There is six inches between the tires now (with the 15 inch wheels) - there is three inches to the fender both front and back and three inches upward to the trailer body. It seems to me all these distances would be decreased by one-half with the 16 inch tires - would all this fit in the wheel well?

If I upgraded to 5,200 lb axles I would still have the 10 inch brake drums as well as a fifteen inch tire - but with a 6 on 5. 5 lug pattern. I note there are ST225/75R15E tires rated at 2,800 pounds and are less than one inch greater in diameter. I think these would fit in the wheel well with the addition of a fourth leaf spring. This would get to the 80% of capability. I have not seen any fifteen inch LT tires. And, my concern with ST rated tires remains.

So, I am still a little confused on the suspension. Does anyone know if a good 15 inch ST tire exists or whether a good 15 inch LT tire exists?


I will go with a weight distributing hitch with sway control. I can't really tell from commentary on the posts and in the reading I have done whether this is required - but, I can see no downside to it - I canlt see how it can be anything but beneficial even if not really required. The Hensley products are extremely expensive - was thinking of going with the Equalizer hitch. My trailer is not all that big, and it seems like it would be easy to use in practice. Does anyone see anything wrong in this approach to hitch?

So - trying to firm up a plan - like everything it seems there are pros and cons - welcome any other insights.

Kevin

Kevin,

You're doing a great job of analyzing the challenges and possible solutions. I commend you for it - this level of thinking and learning is not common.

I agree with your analysis of moving up to 6k axles with 16" wheels and larger brakes. There is an additional choice you may have overlooked. LT225/R75/16" tires on eight lug wheels will provide genuine truck tire capabilities and reliability and are very similar in size to the 15" ST tires which are not worth mention.