Trailer wheels crack - 2 trips, 4 cracked wheels. Why?

Upon relocating cross country from Idaho to Florida with the trailer I built from a 35' crashed 5th wheel, on 2 trips, 4 wheels have cracked. 
History of the trailer build:
The trailer frame required a ton of beefing up obviously because once that trailer structure is removed, the frame of the trailer is like a noodle. The added 1" corrugated semi trailer deck helped a lot. The axles were replaced with 4- 2500lb torsions with a lot of added support for them. We also used many 7"x3" 3/8" x5' long angle steel to build/support the front & rails back to the axles. Also used 2"x6" 3/16" tubing to double up the arms of the hitch and V cut them to bring them in like a goose neck since there isn't a bed up on the deck anymore.  It's very strong now.  It has tool box, winch, big reverse lights, aluminum fenders, 10 anchor points, batteries & 2 spare tires.

So what happens:   
On our first trip, hauling the MR2 & CVCC,  before starting out on the second day, saw a rear tire was flat. The weight of the 2 cars is 4,000 lbs.  Went to air it up with the onboard compressor & it was leaking out of a crack in the steel wheel. Swapped on a spare.  Thought that was really weird. 2nd night, went to start out & checked the tires, again a rear tire is flat & again the wheel is cracked in the same spot. It was on the other side of the trailer but still on the rear.  So now we've used up both of the spares. We made it the next day, unloaded the cars & over night, no cracks.

I called the company & they sent me 2 replacement wheels.  The wheels & tires are load range E, were properly inflated etc. 
Drove back from Florida to Idaho empty & no issues.

The next trip was even heavier with the trailer loaded with our household belongings in a diy box I made & wrapped in a tarp.

Before this next trip, I raised the trailer a bit by re-clocking the axles & lowered the hitch slightly to shift the weight a bit more to the front wheels since I thought maybe there was more weight on the rear wheels, compared to the front.

Took off on this trip & the exact same thing happened. The wheels are fine after driving all day but sometime at night while cooling off, the wheels crack. Always in the same spot,  which is on the bend on the inside of the wheel. 
Made it to Florida with 2 flat spares again,  the last night it was raining when I arrived & the next morning at home the wheels were fine so I suspect the rain kept them cool.  
I called the supplier again & they sent 2 more wheels. They did admit that they had heard of this happening but is rare. They suggested I switch to load range E aluminum wheels to better handle the temperatures. 
Has anyone had anything like this happen?

Stress from turning sharp corners? The back wheels get alot of side load when doing 90 degree turns, I can hear my suspension groaning when I have to take sharp corners.  Just a guess though. I need to che k.i e more often I guess 

Welcome to Florida!

I assume you have verified the wheel load ratings vs. gross trailer weight. Do the wheels make good stable contact with the hubs/brakes before you tighten the lug nuts? The lug nuts should just be holding the wheel against the hub/brake, not pulling it into place.  Are any of them tending to loosen up in service?  If you jack up each wheel does it spin true? 

Nice rig, by the way! 

If those are 5 lug, they're probably similar to what's used on the 3500lb torsion axles.  In that case, I'd say they're not beefy enough for a trailer that big.  I'd go up a size to the 5200lb axles or whatever the individual torsion thingy equivalent is.  It'll give bigger brakes too.  Personally, looking at the proportions of the trailer, I'd also want the axles back a bit further. 

Like to know if they are failing at the same  feature or point on the wheel? Cant picture it from the description.

Why are the wheels getting hot? Define "HOT"?

At first glance, my first impression was that the trailer  and load was too big for the rolling stock. But that is just from here in the cheap seats.

Seems like a good starting point would be to get an IR temp gun to see how hot things are getting. 

Are there brakes on both axles or just the rear? Are both sets working?

The heavier MR2's tires (and therefore its weight) is sitting 100% behind the rear-most trailer axle.  This seems like it would stress the rear-most trailer tires.  

You have a long trailer but I wouldn't say you have an ideal 2 car trailer.

Edit:  what an awesome collection of vehicles!

Empty, I'd guess that trailer weighs two tons. Add the loads pictured and it's over the axle limits. Have you ever run it across a scale ?

Edit: Are the torsion axles actually rated at 2500# for each corner, and what are the wheels rated for? The wheels look like 5 lug ones I use on my 18 foot open deck trailer that has two 3500# axles.

John Welsh said:

The heavier MR2 is sitting 100% behind the rear-most trailer axle.  This seems like it would stress the rear-most trailer tire.  

Good point.  With how far forward the axles are and the way those cars are placed, that trailer is loaded very incorrectly.  A gooseneck should be around 20 - 25% pin weight, that's probably well under 10%.  Correct loading would be MR2 in front and both cars facing engine-forward. 

It also looks like the trailer is tilted backwards.  Torsion axles don't equalize load between the axles at all, so if the trailer isn't level, one axle gets overloaded.  In other words, that rear axle is probably very overloaded.  Size the axles assuming the load won't be split evenly between them.  Also try to get the trailer move level and move the axles back further.  The front axle should probably be a foot behind the current rear axle. 

In reply to rslifkin :

I'll bet that every time you push on the accelerator pedal and the weight naturally shift rearward that the rear trailer axle is carrying nearly 100% of the weight.

Again, it is a long trailer but not really a two car trailer.  Move axles is one option but another would seem to be to just cut some feet off the rear of the trailer.  I would say from rear axle to tail light, cutting it off at about half way between those two points will get you a workable length.  

I can't say why you had same/similar issue with covered load.  It seems to end at about that suggested length.  

But, the covered load probably could have benefited greatly by moving the load even just the one foot forward all the way to the front.  Further more, being covered, I can't comment on the percentage of the real load weight.  

Beefing up the tires/axles as well as loading more forward should solve the problems.  

What rslifkin said.

 "Torsion axles don't equalize load between the axles at all"

So, the rear axle was hauling more weight than it was rated for.

I'm thinking you are fortunate worse things didn't happen.

5 lug load range "E" wheels and tires are rated at 2830#. If the rear axle is taking more than its 50% share of the load then the wheels are overloaded ( I'm ASSuming that the all up weight is close to 10K #). The reinforcing steel mentioned run 10-13 #/ft, so how many feet were added to the tongue and floor area? I haven't found a weight for the decking material mentioned yet.

As a thought, heavier duty axles and the corresponding wheels and tires (which will likely involve a tire like a 235/80R16 or 235/85R16) will make the trailer a bit taller which might resolve the leveling problem on its own. 

Cool trailer project! 

I somewhat agree with what's been posted so far but im also tempering my opinion with my own lazy approach, which is that i'd rather use my brain to work around the limits of something cheap than invest a bunch of time and effort into making something dumb-proof.  With that in mind I would primarily just focus on loading it better and maybe working to make the tongue height adjustable if it isn't already so you can do some fine tuning on whatever you've got loaded. 

If you're trying to use this as a 2-car hauler on a regular basis i do think it's severely limited on what you can carry and how you can carry it, unless you do some of the bigger work thats been suggested about moving and upgrading the axles/wheels. If you mostly plan to move one car at a time it's already way on the awesome side among one-car haulers. The 'breakover angle' from ramps to trailer deck is absurdly good (loaded a lot of lowered cars in my time lol) and that would get a lot worse if you moved the axles back or made them bigger, or cut the tail off. 

As far as the wheels cracking, they're probably cracking due to fatigue which means they are flexing in use, because there's no temperature for a wheel that won't kill the tire way before the wheel. You can almost certainly 'fix' that issue just by bandaiding some stronger wheels onto what you have, but you may also be looking at an alignment issue (contributing constant cyclic deflection any time it's rolling). Any difference in wear from front to rear tires? If the cracked wheels you have are not bent, you could get the tires dismounted from them and bolt 2 bare wheels to the trailer to comparatively check front-rear axle alignment by running a string or long flat bar across all 4 wheel 'edges' and see how that's lining up. 

Also, i LOVE the tow vehicle. 

This is why I love GRM. Any other place someone would have been ridiculed for building a trailer less than perfect. Here, you're commended for doing (an impressive) job under the circumstances and then directed towards possible, valid solutions.

I'll echo to comment about cool car choice. Other than that, I have nothing constructive to add.

The axles are 6 bolt - 2500lb each. We placed them where the old axles were.

There is no noticeable tire wear. We did a lot of measuring before welding the axles in place & it's as good as it can get. When we did the empty testing it tracked very well. Took it up to 90mph & it was great. 

Yes the tongue has @10" of adjustment & I've made some adjusting.

Each axle has a brake & turns free until the brake is pressed.

I'm assuming it's a heat/cooling issue because it never happened until towing for 12-16 hours & it's fine but then sitting & cooling off over night they crack. When it rained, it didn't do it. 

The cracks are hard to explain but it's on the inside of the wheel where it's radiused  & then about 3" in from that the center piece is welded. It's always on that radius.

The 2 cars was a 1 time thing. In the future it will be just 1 car.  The CVCC was as far back as possible due to being @ 1/2" from the winch. I could have removed since it's on a hitch insert. That would have gained @ a foot.

Yes bad things can happen when towing. Somewhere in Wyoming a semi was passing me on the left & suddenly there was  a huge boom. Everyone slowed down & it was the semi's left side trailer tire. Can't imagine if that would have been on the right side right next to me. I'm sure the tire pieces would have done some damage.

I'll raise the axles a bit more & check the temps when we tow & put the load more to the front. 

How hard would it be to add a third axle? Seems like that would be cheaper than replacing all the current equipment with beefier stuff, and would have the added benefit of moving the balance point rearward a bit.

Adding a 3rd axle would be a lot of work & I don't have my shop any more. Also the axles were new but surplus so very affordable, all of the 3/8" diamond plate that I made the fenders from was free because where I worked, the supplier bent 2- 4x8 sheets the reverse from what we needed. I got really good at cutting metal @ tig welding. I was able to go in on off days & nights & use the 480v liquid cooled tig welder.  That's where I got the 3/8" angle also, they were the yellow warehouse shelving forklift guards. The forklift operators were always running into them & we had a nazi safety lady that required them to be replaced if they had the slightest bend. I got at least 10 of them. 
They also scrapped a bad electric forklift that had 4 good 6v batteries. Got those for free, used 2 for the winch. I miss that place for all the free stuff & metal work I got to do. 
 

I'll just make sure loads are more forward & use the back for light stuff if at all.

Honestly I think I would change wheel brands. They have a steel or a forming issue and are probably starting the crack  when they form the wheel. The temp change just finishes it off. 

I've had hubs go up in smoke from heat and never had a wheel fail. If it was a overload problem, the tires would go up before the wheels did. If it was an alignment problem, the tires would show significant wear after the mileage you are driving. 

Is it always the same wheel position? 

Toyman01 (Moderately Supportive Dude) said:

Honestly I think I would change wheel brands. They have a steel or a forming issue and are probably starting the crack  when they form the wheel. The temp change just finishes it off. 

I've had hubs go up in smoke from heat and never had a wheel fail. If it was a overload problem, the tires would go up before the wheels did. If it was an alignment problem, the tires would show significant wear after the mileage you are driving. 

Is it always the same wheel position? 

 

 

yeah, I'm not super knowledgeable with trailers, but I tend to agree with this. Maybe the axle is overloaded, but that's an odd failure if the tires are still fine (and after 4000 miles of overloaded you'd be able to see that on a tire). 

is your brake controller dragging at all? Maybe it's keeping your brakes engaged just lightly the whole time you're driving?

Always the rear wheels. Should I switch to al-you-min-ee-um?

After driving a few hundred miles, are the wheels warm?  You know, warmer than the ambient air temp. 

Tight bearings?  Flexxie wheels?  Is there an RV or Trailer repair shop nearby, either State?  I would drag the trailer along and chat them up.

I would check the hubs/wheels for runout. You could have a wobble along that plane (perpendicular to the wheel face) that fatigues the wheel, and the greater the load the more that flex is transferred into the wheel. 

I wonder if the wheel isn't already cracked when installed and the only thing holding the air in is the paint. The wheel warms up and expands. Then the slightest shrinkage would cause the paint to fail. 

It's been parked until I build a shed to store the last of my outdoor & garage stuff in. Right now it's my storage shed on wheels. 
4 different wheels though. They are made in China.