October 09, 2014

Trailer tires

The subject of trailer tires is hotly debated on any of the online forums. A lot of people have an opinion, and a good percentage have had tire problems at some point. In fact, if you haul a trailer or fifthwheel for long enough, it is not a question of "if", but "when" you will have a tire-related issue. I will discuss in this post, my own experiences with tires.


Before we factory-ordered our Pinnacle, we visited the Jayco factory in Middlebury, IN to have a tour of the production line while Pinnacle fifthwheels were being built. After the tour, we had a sit-down meeting with one of the managers, and one of the questions I asked was: "Would Jayco be willing to substitute better tires for an added cost?" The answer I received was "No, the tires we supply are adequate!"


We were pleased with most other features of the Pinnacle, and the quality reputation of Jayco, so we went ahead and ordered our new home with the factory-installed tires, which were GoodYear Marathon tires in 235/80-16 size. These tires were manufactured in China, as are almost all ST (Special Trailer) tires available today. The weight rating of these tires is 3420 lbs at the maximum pressure of 80 psi.

This rating may, at first glance, seem to be adequate. The axles on the Pinnacle are Dexter 7000 lb, but they are derated to 6800 lb because of the tire limitation. If the fifthwheel is loaded to near the factory GVWR (Gross Vehicle Weight Rating) of 15950 lbs, and if we assume a pin weight of 20% or 3190 lbs, that gives a weight per tire of 15950 minus 3190, divided by 4, or 3190 lbs. The weight distribution is almost never the same from side-to-side, so it is possible, even likely, that two of the tires will be operating at, or over, their maximum load capacity.

I was aware of all of the above, but I decided to stay with the Marathons, install a TPMS (Tire Pressure Monitoring System), and watch the pressures diligently. I also took care to keep the speed below the 65mph limit of ST tires, at most times driving at 60mph.

Our tire failure
We did 2 return trips from Ontario to California on the Marathons. At the beginning of the third trip, I noticed odd wear patterns on a couple of the tires, and found that it was becoming difficult to install my X-Chock wheel chocks between the tires (I use these to help stabilize the rig when parked). I should have heeded these warning signs. Westbound on I-20 in Louisiana, I suddenly got a pressure loss warning from the TPMS. Luckily, I was passing a highway off-ramp, and I immediately pulled over and stopped in a safe spot on the exit lane. I went back to look at the tire, and it was completely flat.

The TPMS which I had installed two years before certainly paid for itself that day. Without it, the tire would have failed catastrophically, resulting in major damage to our full-body-painted home on wheels, caused by the disintegrating tire flailing around under the wheel well.

Cause of the failure
After removing the wheel and replacing it with the spare, I examined the tire closely. The circumference of the tread was no longer round; it had bulges which were quite obvious. At one point on the tread, the internal steel belts had broken, pierced the tread and were protruding through to the outside. This is what caused the pressure loss. We proceeded, with the spare tire mounted, to a campground near Shreveport, LA, and set up for the night, so we could contemplate what to do next.

We considered our options, and determined that we had several choices:

  1. Replace the bad tire with a new GoodYear Marathon, which was available locally. Cost $150.
  2. Replace four tires with GoodYear G614 RST Load Range G tires, using the same wheels. Our original wheels were rated for 110psi, which these tires need to achieve their load rating of 3750 lbs per tire. Cost $1500.
  3. Replace four tires and wheels with 17.5 inch commercial Load Range H tires, which are rated at 4805 lbs per tire at 125 psi. Cost $2400.
We decided on option 3. Although the cost was highest, it would give us a substantial safety margin on tire load capacity. Tread depth on these commercial tires is 16/32, compared to 10/32 for the Marathons and 12/32 for the G614. An added advantage is a speed limit of 75 mph. The outside diameter of the 17.5 inch tires is almost identical to the Marathons, because the tire size is 215/75-17.5, compared to 235/80-16. Of course, new wheels were required.

We ordered the new wheels and tires from trailertiresandwheels.com. They were very helpful in assisting us with the selection, and they mounted and balanced the tires on the new wheels, and shipped the assemblies to us. We decided on Sumitomo tires, which are a quality commercial tire manufactured in Japan. Sumitomo are quite popular in the commercial truck and trailer business. The service we received from Trailer Tires and Wheels, who are located in Ohio, was exemplary, specially when we consider that it was a holiday week.

Our dilemma...we were near Shreveport, LA, and it was December 22. We had planned a 4 day stop over the holiday at Boerne, TX, which is in the Hill Country near San Antonio. We decided to continue to Boerne, and have the wheels shipped via FedEx to San Antonio, but they would be delayed because of the holiday shutdown. One problem - we had no spare tire! The drive to Boerne was undertaken very carefully, at speeds at or below 55 mph. I did not want another tire to let go, as it would have been inconvenient, to say the least.

Thankfully, we reached Boerne, TX on December 24, and settled in for an enjoyable stay over the holidays. We stayed at Top of the Hill RV Resort, which is a friendly, clean campground with a great view, and we visited famous Fredricksburg, TX for some fine German cuisine. The wheels arrived on December 29, and we drove into San Antonio and picked them up at the FedEx freight center. We installed the wheels that afternoon in the campground. Next day, we took the old wheels and tires to a local tire dealer, who unmounted the tires to dispose of them. The tire shop owner shook his head in disbelief when he saw the Marathons, which had plenty of tread left, but were misshapen because of the separating belts. It was only a matter of time before another would have failed. He said that he sees many destroyed trailer tires, but they are usually shredded remnants wrapped around a rim. We took the original 16 inch aluminum wheels with us, to sell on Craigslist in California. We ended up selling the wheels for $150.

I no longer worry about tires. I feel much more confident now that we have good quality commercial rubber under our home, and it was worth the expense. I also appreciate the value of a tire pressure monitoring system. The downside - we are less wealthy by $2400.



  1. Great article on RV tires. I won't be buying my first RV for another two years, but I'm starting my research now. I don't even want to look at a manufacturer that doesn't use a 17.5 inch wheel.

    1. Unfortunately, few manufacturers offer these 17.5 wheel/tire assemblies as an option, except for Doubletree (Mobile Suites), and a couple of others. Many manufacturers of larger fifthwheels offer the GoodYear G614 as an option, but these tires seem to be somewhat problematical, with many failures. One option is to budget a couple of thousand and upgrade the wheels and tires immediately after purchase, as I should have done.

      Remember, a TPMS, which can be had for $250, can be a real "rig saver".

  2. We too upgraded to the 17.5 wheels and tires after a similar situation. It amazes me that Keystone continues to use these tires even though they must be aware of this issue. Will it take a death or serious injury and lawsuits before they change their ways?
    Safe travels!