Community Forums

MDWood · 03-22-2025, 02:44 PM

I am considering adding a tag axle to my 2019 Thor Chateau 31W...
It comes with a GVWR of 14,500lbs. Its current curb weight is 13,920 with a half tank of fuel (55 gallon total tank)and no water and me 180lbs on board.
Thats with no food, or tools, or cleaning products, or cooking supplier, grill or dishes, or bedding and clothes, or wife and one child and 2 dogs.
To be fair, I added much needed things to the RV since I bought it. Things like a Spare Tire, wow what an idea, Heavy duty Sway bars a Trak Bar and air bags for the wet noodle ride. Finally 2 more AGM batteries for the house side to keep the fridge going for more than 2 hours. I know those all add up to weight but they are all what i would call Necessary for road trips.
My weight with everything we need to travel with is 16,780lbs

I'm pretty upset that RV makers in my price point take advantage of all of us simply not knowing that we can only add 500 to 800 lbs of people and stuff and then your OverLoad!! My rv claims to sleep 6! So 6 at 180lbs each is.... 1080lbs!! I was much better off before I got the bright Idea of weighing the rv at a Loves. Then I read up and find that many times RV owners are sued for accidents for being overweight or not properly loaded evenly.

I've taken it from Florida to Northern Maine several times. Ive had a tire or two go out. I now understand why. I'm going to buy better tires for the load but that will not fix the problem. I feel Thor should pay to install a tag axle and then re-rate my rig for more weight. I know where that request will go.
So has anyone here or that you know added a tag to a Class C? i know I can buy a used E-450 rear axle for 2k. then I move the fuel tank and sewage tanks rearward. Engineer air bag lift and drop brackets for the axle and plumb the brakes.
I work full time so this will take about a year for me.

I hope to hear that I'm not the only man thats taking something like this on. I hope to hear any comments or opinions about what I want to take on.

Btw, I still owe 58k and make my payments, the dealership will only offer me 43k at most for a trade, thats why this seems cost effective.

Ron Dittmer · 03-22-2025, 02:51 PM

Chassis over-load by 2300 pounds is surely concerning, but as you have first-hand experience, the greater concern is "over-loaded tires" that are ripe for blow-outs.

I wouldn't drive that rig on another trip until replacing the tires with 121C commercial E rated tires because each tire can carry an extra 550-600 pounds (at 83 psi).

It is appalling that RV manufactures are permitted to build rigs that are so close to GVWR.

MDWood · 03-22-2025, 02:59 PM

I am planning on getting the Michelin Agilis Cross Climates rated at 3195lbs at 80psi. The current tires are Hankook Dynapros rated at 2680lbs at 80 psi.

Ron Dittmer · 03-22-2025, 03:05 PM

Quote:

Originally Posted by MDWood

I am planning on getting the Michelin Agilis Cross Climates rated at 3195lbs at 80psi. The current tires are Hankook Dynapros rated at 2680lbs at 80 psi.

Be careful. There are two types of Michelin Agilis Cross Climate tires. The ones I have are the standard E rated ones that are ideal for my load. Be sure to get the 121C versions that are rated to a max of 83 PSI. There is a visual difference in the thread pattern, an easy indicator as to which ones they are.

Don't let anyone sell you the wrong Agilis tires by mistake.

d23haynes57 · 03-22-2025, 03:12 PM

It sounds like you outgrew the RV. Even getting past the tire and axle ratings the box of the rig also has limitations and overtime there will be signs that the body is being tweaked.
The real chassis for that probably ends shortly after the rear axle spring hangers. After that is all bolt on extensions. I have seen many that showed sign of failure behind the rear axle just from carrying the weight of box and the trailer hitch being used.
Probably the best solution would be to upgrade the rear axle and springs to maybe a 17,500 which would be 19-inch wheels and then doing a lift kit or something to get the front to that height and also take a larger tire and wheel. You have to give some thought to the liability of this level of modification.

As for the financial hit, the market is down so while you are getting less than desired a replacement coach will also be less especially if staying used. Trading in for new the main reason that MSRP is so much more than actual pricing is to give them room to make deals with financing. They can twist the numbers and add that lost value to the new rig and somehow still make the down payment percentage and get it financed. However, as you are finding out, a 15- or 20-year loan is almost just paying rent. The interest is almost all of every payment. Speaking of interest, have you been able to claim that on your income taxes?
Another option is to sell it privately and just fund the difference. If the engine blew tomorrow, how would you deal with that? Consider this as a similar event.

MDWood · 03-22-2025, 03:19 PM

I had looked into new rims that could handle more PSI but that turned into a deep rabbit hole of money! 83psi is pushing it with my steel rims. I use TireMinder monitors and see my tires go up to low 90s PSI at 110 degrees. Its quite amazing what abuse the tires take.

d23haynes57 · 03-22-2025, 03:29 PM

Tire pressure going from 80 at rest to 90 at speed is not even of concern. My unloaded pickup truck does that. I get a 6-psi difference based on being parked NY in winter and then Barefoot Bay.

Ron Dittmer · 03-22-2025, 04:04 PM

The E350/E450 steel wheels are stamped "80 PSI MAX" which considers such wild environmental fluctuations. 3 PSI more than the max "cold" is neglegible.
I would add the full 83 PSI which just might lower those fluctuations a little.

Unplanned Tourist · 03-22-2025, 04:36 PM

People may laugh, but have you thought of using a trailer axel with smaller tires for the tag? A 4,000 load rated axel with air bags, trailing arm suspension would do. Easy to drop the bag pressure for tight turns in a CG and boost the pressure up again out on the road. Tire scrub will likely be minimal, just be sure to put a track bar on it.

Heck, you could even put a 7,500 pound axel under there for under $1,000.00 plus tires.

Axels are available in various widths and most come with electric brakes.

Be sure to take pictures and let us know how it works out. Dare to be different

Now the wheel wells might be a problem.

ChrisDParise · 03-22-2025, 04:51 PM

I understand your plight but adding a tag axle to a Class C? You would lose basement storage for sure and how are you going to cut the wheel wells?

Even if you could, it will cost you in time and materials some of which you're under water on your loan - and the opportunity cost of rving while working on it.

baraff · 03-22-2025, 05:10 PM

Quote:

Originally Posted by MDWood

I am planning on getting the Michelin Agilis Cross Climates rated at 3195lbs at 80psi. The current tires are Hankook Dynapros rated at 2680lbs at 80 psi.

I have these tires. They are the Cross Climate C ( C for commercial)
They have a distinct tread pattern and are uni-directional, meaning they cannot be rotated like conventional tires. They can only run in one direction. Only front to back rotation.
The Cross Climate C tire is rated 3195 @83psi max. I've had them for about 4 years and am very happy with them.

MDWood · 03-22-2025, 06:42 PM

To add to some of the comments, I have looked at the basement storage I would loose.... Its a joke, One small compartment on pass side and I would move the sewer further back on the drivers side. I have had the pleasure of working on several Class C's over the years and the wheel openings are just plywood skinned on the outside with fiberglass skin and tin skin on the inside of what is referred to as the skirting( aka sidewall below the floor line). If anything adding the Tag and stiffening the frame extensions will add basement space. My 31 footer has very little behind the axle because they knew there was a weight issue. I wanted to add a bumper platform in the rear and saw the 2X6 C channel with only two little perpendicular braces. They seem to actually rely on the hitch and the rear bumper to add frame rigidity! So I picked up some steel to make a nice rigid frame back there and Never moved forward after I saw the over weight issue.

MDWood · 03-22-2025, 06:43 PM

I like all the input about the tires! I will make sure to follow your guidance.

d23haynes57 · 03-22-2025, 07:22 PM

Getting back to the tag idea, as you lift weight off the rear axle you will be adding to the front. Part of your plan probably needs to include moving the existing rear axle forward. There are reasons that many class C are moving to the truck-based platforms.