A tip about tires

I’ve written about tires so many times in the past four years that I am wary of bringing up the subject again.   I have to wonder how many blog readers’ eyes have glazed over permanently.   But I keep learning new things, and I feel obligated to share them here in the hopes that these lessons will help someone else.

A few weeks ago I had mentioned on the blog that we had unusual tire wear along the outer edge of some of the Airstream’s tires, and this was the thing that caused us to go to Jackson Center for an axle alignment.   As it turned out, the axles were out of alignment. After the service, I resolved to keep an extra sharp eye on the tires, to see if the wear returned to a more even pattern.

This morning, after yesterday’s 350+ mile tow, I noticed the left rear tire was looking very funky.   Wear was occurring rapidly in isolated spots, and there was a distinct bulging in the tread.   Those are the signs of a belt breakage inside the tire, and I’ve seen them before.   We got some local advice and towed the Airstream a few miles over to Mill’s Fleet Farm in Wausau for a replacement.

These days, when I have a tire problem, it is my habit to remove and reinstall the tire myself.   This saves a lot of hassling and potential screw-ups by technicians who (a) don’t know the proper way to jack up an Airstream; (b) will use an air wrench to over-tighten the lug nuts; (c) want to argue with me about using tire pressure sensors (“Just throw those things away, they’re the cause of every stem failure I’ve ever seen.”)

So in the parking lot we removed the left rear tire (a Carlisle) and sure enough, it was a disaster.   The tire rolled like a jelly bean, and had bare patches on it.   It looked fine the day before, which shows how fast they can deteriorate once a belt starts to separate, break, or shift.   We rolled it over the shop, where it was quickly replaced with a fresh tire.

Then I took a careful look at the other tires and discovered that the left front tire (a PowerKing TowMax) also looked a little suspicious.   I asked Jason, the Service Manager, to take a look and he agreed it was probably also suffering belt breakage.   We removed it out of caution and confirmed that it was indeed out of round.   While it wasn’t as bad as the rear tire, it was heading that way and needed replacement.

So now the question was, why were these tires failing?   At first I was theorizing that the tires were stressed.   They had been wearing in a particular way before the axle alignment, and now they were being forced to wear differently.   Could the change in alignment be the cause?

Then Jason pointed out something interesting to me.   Both tires had been patched (we have rolled over a lot of road debris like nails and screws in the past year).   Both tires had belt separation centered in the exact spot where the patches were installed.   At last, we had a smoking gun.

The problem was that these were “flat patches”, meaning that they covered up holes from the inside of the tire like patches on your blue jeans.   Flat patches do a good job of holding air, but the original hole in the tread can still allow water to get inside the tread.   Over time, that water will rust the internal steel belts of the tire, and suddenly they break.   This is what I believe happened to my two tires.   Left unattended, the next step is a blowout.

The Rubber Manufacturers Association says not to use flat patches.   The recommended and best way to patch a tire is with a patch plug, which is a patch that also fills the hole permanently and keeps it dry. Too bad that the last few shops to work on my tires never mentioned this option.

Well.   I am glad that tire inspection vigilance prevented us from having a more serious problem, but on the other hand I wish I’d known about patch plugs before.   A pair of them might have saved us from buying $200 worth of new tires today.   I may begin carrying a patch plug in my spare parts kit, just so I can hand it to a tire shop guy if he doesn’t have one.

The two tires on the right side of the trailer are fine so far.   I don’t recall if either of them has been patched in the past, but they are wearing appropriately at the moment so I’ll just keep an eye on them.   Both of them, by the way, are Goodyear Marathons, and the rear one is actually nearly worn out, which suggests that it is approaching 30,000 miles.   My experience with numerous trailer tires over the years has been that no particular brand holds up any better than the rest, so I buy whatever is available.   At this point we have three different brands rolling on the trailer.

Interestingly, I had been noticing since Grand Rapids that our fuel economy was mysteriously declining.   We normally get 14-15 MPG towing with the diesel, and suddenly we were getting 12.5 – 13.3 MPG.   It seems that the tires were the problem.   Now that we’ve replaced the bad tires, we are back to normal fuel economy.   The broken belts “squirm” as the tire rolls, and in addition to causing rapid tread wear, this apparently increases the rolling resistance as well.

We are in Minneapolis tonight, parked on the street in a quiet neighborhood (with permission of the homeowners and their neighbor).   Local law says we can stay one night if we don’t unhitch, and that is our intent.   We had dinner on the deck with our hosts this evening on this balmy 82-degree September evening, and will be heading to Bloomington for routine car maintenance tomorrow.   Now that we are here, we are done with big-mileage days for a while.


  1. John Irwin says

    I had an E-rated Maxxis tire that bulged out in the center and looked like a bicycle tire with only the center 4″ touching the ground. The tire actually grew about 2″ in circumference and was difficult to get out of the wheel well; I had to reduce pressure to dismount it. The tread was good with about 15000 miles on the tire. Tread was good and wear was even. Tire shop said they get an occasional tire with this problem and it will lead to a blowout.

  2. Brett says

    Being a Wisconsin Native, all I can say is I am sooo jealous you got to experience Fleet Farm. I know we have Tractor Supply here(FL), but they are nothing compared to the service and selection…. Glad you caught the issues early… I blame the VT summer parked by the lake for the rust :-)

  3. says

    a cheap tire plug kit from an auto store gives the basic idea of items needed. improve from there: a quality hand insert tool for installing plug. vise grips, needle nose pliers, 1/8″ round file, can of rubber cement, small tubes of rubber cement, drill & drill bits, small air compressor. rotate wheel to allow you to be comfortable lying on ground to remove object. focus on direction/ angle of removal. clean hole with file and or drill as little as necessary. use only rope type material for steel belts. purchase box of 10-20 short sticky twine type ropes. unravel 1,2 or 3 twines as determined by object size. load twines on insert tool. best of buy pro type insert tool. apply good amount to hole area, also a good amount to entire twines. very slowing insert rope/twines into hole, rotate a little if necessary, leave a reasonable length outside of tire making sure the loop of twine has entered the inside of tire. next is the tricky part. remove insert tool leaving twine loop inside tire and some twine outside of tire. might have to repeat procedure. always leave some twine outside….you can pull it all out and try again. air tire up to about 70% and if possible wait a bit. check for air leak. if all is good, cut excess off using sharp razor…same height or a little more than tread. bowes tire suppliers have the boxes of sticky twine rope, strong insert tool [saves hands], and maybe a step down size round file for small or medium size holes. about once a year buy fresh rubber cement.

  4. Lou says

    Yes, Peter, is right on with his instructions. Larry and I carry a kit in each car just for this very reason. We have used them on several occasions. And even I know how to use it!!! Larry has taught me well! Hope you get a couple of kits for your vehicles. Wish we had asked you if you had them when you were here!

  5. says

    We do carry a tire plugging kit, actually two of them. One is a very simple Dynaplug system and the other is a traditional plug. We also carry a CO2 inflator by PowerTank to top off the tires. This setup was chosen because the tow vehicle has run-flat tires and no spare, but it is equally applicable to the Airstream as well. I haven’t had the opportunity to use it yet.

    If I did plug a tire on the road, I’d regard that as a temporary repair until I could get to a tire shop and have it patched as well.

  6. says

    We “plugged” one of the tires on our Airstream this summer about an hour from Tok, Alaska. When we reached Tok, the tire was flat again and the tire guy repaired it with a patch, which is still holding 1,000 miles later. As you say, I think a plug must be considered a temporary thing.

  7. says

    Excellent post, Rich. Ironically last week we had our first tire repair and only learned how enlightened our mechanic was by reading about your experience. One thing I did know (but didn’t need to insist) was the hand torquing of the lug nuts.