Troubleshooting Rear Tires Wearing on Inside for Dual Axle 5th Wheel Trailer

Question:

Fifth-wheel trailer: 2019 Grand Design 367 BHS Reflection 41 Truck: 2018 Dodge Ram 3500 SRW Diesel Cummins 6.7 crewcab, 6.4inch bed. The trailer is connected to the truck through a Reese first generation Goosebox. Trailer tires: Carlyle 14 ply G rated second set of tires on the rear axle Axles: 2 x Dexter 8,000lbs each Our last CAT scale weight was 12,420lbs on both rear trailer axles. Problem: We had to replace rear axle tires twice because they are wearing on the inside very rapidly. I used a tread meter to confirm that both tires are evenly worn on both sides. The front axle tires barely show any wear. The tread on the tire that is being worn the most its the one closest to the edge of the tire on the inside for both tires equally on both sides. We had our bearings repacked back in May 2019. That did not fix the problem, plus we were told that there were no significant issues with the bearings other than the fact that they were missing some grease from the manufacturer. We had the axle looked at by three different trailer shops, and all of them agreed that it still had its shape and that is it was not bent. It was never taken off the trailer to be tested further, all of those assumptions were made through observation only. Why is it happening? We put over 17,000 miles on this trailer this yeat. Im afraid to travel any further until its fixed. Any help or suggestion would be greatly appreciated by our family.

asked by: Olga

Expert Reply:

Thank you for all of that information.

From everything that you described it sounds like you are overloading your rear axle. Even though your axles are rated for 8K each and you only have 12,420 lbs on your axles, if your rear tires are wearing on the inside tread then you have too much weight over the rear axle and you need to adjust cargo around in your 2019 Grand Design 367 BHS Reflection 41.

Axles naturally have an arced shape and when they are weighed down correctly they straighten out some which then promotes even tread wear. When an axle is overloaded it actually bends down so much that the arc reverses (so it is pointing down and has more of a "u" shape) and that then causes your hubs to sit at an angle and wears down your tires.

One thing you can do to help make sure your axles have the weight evenly distributed is to make sure the pin weight of your trailer is about 20 - 25% of the loaded weight of your trailer. Load up your trailer as if you were going on a trip and then go to your nearest commercial scale. Weight your 2018 Dodge Ram 3500 without your trailer coupled and then weigh your pickup again with your trailer coupled. The difference in weight is your pin weight. (see attached photo of bumper pull trailer example)

If you do find that your pin weight is fine then you need to look into getting that rear axle replaced. It wouldn't help to have the suspension looked at as well.

I have also linked our selection of load range G tires that you can filter through if you currently need to replace them.

expert reply by: Jon G