I had a blowout on a Kumho Radial 857 trailer tire today. I believe I have the honor of being the first on this forum to do so, so I sort of feel honored. The details:
- blowout occurred 80 miles into the trip today
- I had checked tire pressure before leaving, and confirmed it to be around 63 psi. According to Kumho, that should have given me a load rating of 2146 lbs per tire, or ~4,300 lbs total. I haven't weighed my TM yet, but given a generous gross weight of 4,000 lbs and a conservative tongue weight of 600 lbs, that would mean only ~1,700 lbs on each tire, well within the rated range.
- We were loaded as we always do for thousands of miles and probably 30-40 trips -- toilet charged, fresh water tank and hot water heater full, and a 3 drawers of clothes. Fridge was stocked, but that's about it. The cabinet under the rear bed is mostly empty, I have 2 T-105 batteries, pots and pans, and 3 camp chairs.
- the tires were 3.5 years old based on date of manufacture. They had been in service for 3 years, and had been used regularly, on average once a month, but a few times (maybe 3) they had gone without being moved for 3 months.
- I was going 60 MPH
- It was about 65 degrees at our house when I left; within 1 hour into the trip, it was 98 degrees outside, so we had been running in that temp for around 1.5 hrs
- It happened on the passenger side, so my new shield around the plumbing that I installed THE DAY BEFORE YESTERDAY wasn't tested.
- This blowout happened on the same side as our first blowout with a Marathon, which presumably has a lighter load than the driver side due to no water.
- I had just repacked the bearings about 6 weeks ago. We did a 15-hour roundtrip drive immediately thereafter in 70 degree temps, and the hubs were lukewarm at best; definitely no where near hot.
- Both tires, wheels, and hubs were very warm. I could grab hold of the hub for a good 30 seconds before it starting getting uncomfortable.
- It appears the tread separated, but there is what appears to be a transverse tear across the tread. I'm not sure if that is a cause or effect.
- my custom made replacement wheel well (with no wheel well modification done) worked like a champ. 14 or 16 gauge (I can't remember) galvanized steel, welded at all seams. Zero damage, and barely even a scratch to the well.
- I looked for any physical signs of foreign objects that would have contributed to failure, but didn't see anything.
Amazingly, between changing the tire myself and getting the spare replaced 5 minutes down the road, we were only delayed 90 minutes. But unfortunately, I think, they did not have any Kumhos. So I ended up getting a Maxxis 205 75/R14, but it's max load capacity is only ~1750-1800 lbs at max psi. Plus, it's a slightly smaller tire than the Kumho -- probably an inch smaller in diameter -- so if I ever have to mount it, I'll be towing with 2 slightly different sized tires. Probably not a huge deal, as the doughnut spare tires are way smaller than regular car tires, and you can get around just fine.
I'm not sure what to do at this point. I concede that the tires are getting up there in age, but I didn't think I was at the point of risking failure. So what was the problem? And what should I do? My options as I see:
keep going with existing setup, with two 3.5 year old Kumhos and one lesser load rated Maxxis -- we have 7,500 miles left on this trip.
dump the Kumhos and get 2 new Maxxis tires to match the spare, although this puts the load rating back down to what the Marathons were.
chalk it up to age, and buy 3 new Kumhos, and try to sell the spare back to whatever deal I buy them from.
I should note that I will be at the TM factory next week, but that's a few thousand more miles down the road. I'm not sure what my options are in upgrading to 15" wheels. I have the older style wheel wells, and I am very close (maybe 1" IIRC) from the frame cross member in back of the wheel. My TM tracks very slightly to the right due to the factory welding the axle about an inch or so (IIRC) further back on one side vs. the other. Could that contribute to failure, or would that just result in uneven wear, similar to a car out of alignment?
What would you all do? We continued on for another few hundred miles, where the temp ranged from the mid 90's to the low 100's. We're just outside of Vegas tonight, and we're headed to Utah tomorrow, where it is supposed to be just as hot.
This is very, very frustrating.
Dave