RV Tech Q&A: July 2020

Cracked tire rim on orange background

Fifth-Wheel Cracked Rims

Red letter QAfter removing the cover from our fifth-wheel after its long winter’s nap, I noticed a low tire on the right rear. At first, my husband and I thought that it had lost pressure due to the cold while sitting for the winter. After taking a closer look, my husband found multiple cracks in the rim. After checking all the other tires, we found the left rear rim was also cracked.

Is this normal? The fifth-wheel is a 2014 with all-new heavy-duty tires and is used in our state of Ohio two out of three weekends in the camping months and usually one out-of-state trip in the fall. Is this a product of the cheap tires that manufacturers put on RVs now, and, so assuming, are they cheap rims? Or is there something we are missing? We’re wondering if other RVers have reported this problem.

Should we buy four new rims? And can you offer any advice to help keep this from happening again?
Debbi McCoy | Rome, Circleville, Ohio

Green letter ADebbi, cracking rims is not at all normal, and the cause should be determined right away. Yours is the first such letter we’ve received about rim cracks so the problem doesn’t seem to be too widespread among our Trailer Life readers. The only trailer-wheel recall we could find was for 16-inch HiSpec cast-aluminum wheels made from 2010 to 2012. Since your fifth-wheel is a 2014, these wheels should have been out of circulation, but without knowing your specific trailer make and model or, for that matter, if it has steel or cast-aluminum rims, we can’t say for sure. It would also have helped for us to know where the cracks were located, such as in the bead seating area, where the center meets the outer part of the wheel, and so on.

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Cracked wheels can happen for any number of reasons: casting issues, overtightening of bolts, overloading, road hazards and, most strikingly in this case, tires that are too high a rating for the rims, requiring pressure beyond what the wheel is designed for.

The first thing to do is to look at the rating of the wheels and compare that to the new heavy-duty tires. The wheel data is stamped on the back of the rim or spokes, and the rest of the wheel data can be found on the manufacturer’s website.

Next, if that is OK, ensure that your fifth-wheel is not overloaded or exceeding the gross vehicle weight rating (gvwr), gross axle weight rating (gawr) or the tire and wheel rating. Because you’re having a specific issue involving multiple cracked rims, we recommend that you get the trailer weighed by wheel position, not just by axle in this case. Information on weighing by wheel position can be found at www.rvsafety.com.

Towing Mirrors

Red letter QLast year we purchased a 21-foot 2018 Keystone Hideout trailer. Our tow vehicle is a 2007 Toyota FJ Cruiser 4×4. The truck has no issues towing the load; the issue is with the mirrors. The mirrors on the FJ Cruiser are very tall and narrow. I discovered on our first outing that they did not stick out far enough to see beyond either side of the trailer. I was scared that I would try to go around someone and inadvertently hit a vehicle with my trailer!

I tried some of the mirror extensions, but the existing mirror housings are too tall and narrow for them to stay attached. I called Camping World, and they offered the same mirrors that I had already purchased. I even went as far as contacting Toyota USA, and got the equivalent of a cyber-shrug and a curt “We can’t help you.”

I am not looking for “pretty.” I am looking for “safety.” Do you have any suggestions? Our trailer has been sitting since it came home, as we do not want to have any problems.
Ron Buchanan | Newton Grove, North Carolina

Green letter AThere are different towing mirrors available today, some of a general-fit nature and some designed for specific vehicles. Among the best we’ve used, on a wide variety of vehicles, are the McKesh Portable Towing Mirrors from Hensley Manufacturing (www.hensleymfg.com). These mirrors are well designed, widely adjustable
and will definitely give you that past-the-trailer view you’re looking for.

Triple-Axle Tire Sliding

Red letter QMy wife and I hope to be toy-hauler owners in the near future. The toy hauler will probably have three axles. What I have noticed in person and by watching YouTube videos is that one or more of the tires can stop turning and just start sliding when backing multi-axle trailers. This is painful for me to watch — hearing the sliding of the tires and the creaking and popping of the trailer. This tells me that there are a lot of forces at work on the trailer.

What kind of damage is this doing? Could it bend a frame? Does it throw the axles out of alignment, or did the trailer manufacturers foresee this problem? Will it break belts in the tires, or are the tires, wheels, bearings and axles sturdy enough to withstand the pressures of sliding sideways on asphalt or concrete under the heavy loads of a fully loaded toy hauler?

I contacted Lippert and was told that it is OK for the trailer tires to slide but to try not to make a steady diet of it. But since I was talking to the trailer-frame manufacturer, I felt like I was getting a bit of a sales pitch. I know that in real life it will not always be a straight shot, and there may be times when sliding tires will be necessary to get into that parking spot.
Jim Rath | Lee’s Summit, Missouri

Green letter AA triple-axle trailer pivots, in a turn, on the three axles, and that means something has to give since none of the three axles has a steering capability. As you’ve observed, that means that a sharp turn, such as backing into a campsite, will produce some lateral tire motion that manifests itself as the front- or rear-axle tires sliding or, at the least, being pushed sideways and tucking somewhat under or away from the body due to suspension spring and spring-hanger flex. This can also be accompanied by the tires distorting and flexing sideways relative to the wheel. This flex is considered normal.

While no tire abuse would be better than even a small amount, the good news is that this happens infrequently and usually at very slow speeds. Tires designated as Special Trailer (ST) tires are said to have stiffer sidewalls to help accommodate sidewall flexing, but Light Truck (LT) tires also have strong sidewalls due to their more-utilitarian load-bearing nature and intended use.

As long as the tires are correctly rated for the load they’re supporting and they’re properly inflated — the usual factors in keeping tires in a good, serviceable condition — a bit of side-sliding shouldn’t hurt them and can’t, in any case, be avoided during sharp turns. The best practice, however, is not to leave the tires and suspension in a torqued state, pulling ahead and backing up straight to relieve the stress before disconnecting.


Have a Tech Question?

Email [email protected] and include your full name and hometown. Selected letters will be answered in the monthly RV Clinic column, but time does not permit individual replies.


Man leaning over engine wearing blue shirtJeff Johnston served as technical director of Trailer Life for 20 years and has been an RV enthusiast, mechanic and writer since he could hold a wrench. In his monthly RV Clinic column, Jeff replies to Trailer Life readers’ technical questions about RVs and tow vehicles. He also serves as associate producer of Rollin’ On TV, a nationally syndicated television program for RV enthusiasts.


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