Monday, September 25, 2023


When to replace tires? Can you drive on one “dual”?

RV Tire Safety
with RV tire expert Roger Marble

I was reading a magazine aimed at motorhome owners and there was an item about a man that suffered an RV tire failure. It was one of his rear duals. The RV owner reported that he decided to drive to the nearest tire store, where it was suggested that he replace all six tires. The tire dealer had to educate the RV owner about the life of tires in RV service being 10 years or less, with many recommending that tires be replaced after six or seven years.

The magazine did offer a brief explanation on how to “read” a tire DOT serial and learn its age.

IMO, the magazine missed an opportunity to further educate its readers with a warning of the damage that was probably being done to the mate of the tire that failed.

First off, there is a good probability that the tire, being more than 10 years old, failed from a belt/tread separation. We can’t be sure, as the RV owner didn’t have a TPMS, so we don’t know if he could have avoided the problem of a “blowout” or “run low flex failure” on the interstate. We do know if there was a slow air loss, the tire that did not fail was being run with ever-increasing overload, for as the companion tire lost its air the load on that end of the axle was being transferred to the fully inflated tire.

In the tire industry, there are tables that provide information on how slow you need to drive as you increase the tire load above its normal load capacity.

Basically, you need to run no faster than 40 mph if you are running 107% of the rated load.

If you want to run 113%, you can drive no faster than 30 and the max speed drops to 20 mph if the overload is +21%.

Since our RV owner was running at 200% load, I would estimate that maximum speed he could travel without doing damage to the “good” tire to be no faster than 5 mph, and even that is questionable as there are also distance limits for those conditions.

If you have a tire failure, no matter the reason, you need to change out the failed tire and should not attempt to “limp” home on its companion. If you are concerned for your safety on the side of the road, you need to be aware that driving over 5 mph means you need to have the companion tire also replaced – no matter its age. As always, when changing tires in a dual position you must also match the pair as covered in this post.

Read more from Roger Marble on his blog at




Roger Marble
Roger Marble
Retired Tire Design and Forensic Engineer w/50+ years of experience. Currently has Class-C RV. Previous Truck Camper, Winny Brave, Class-C & 23'TT. Also towed race car w/ 23' open trailer and in 26' Closed trailer. While racing he set lap records at 6 different tracks racing from Lime Rock CT to Riverside CA and Daytona to Mosport Canada. Gives RV and Genealogy Seminars for FMCA across the USA. Taught vehicle handling to local Police Depts


  1. I just had a “mechanic” tell me not to switch my front tires, left to right. He said they would be running backwards to what they have been running and it would wreck them.

  2. David. Sorry, you had problems but you did the right thing. Do you run a TPMS? Always knowing you have enough air can eliminate one of the two major reasons for tire failure. That being Run Low Flex Failure. The other major reason for failures is belt separations. These, however, can many times be avoided by not overloading or over speeding your tires. Covering them to keep out of the heat from the Sun and to do a complete inspection as outlined in this post.

  3. To Many RVers don’t have a clue about TIRES or TIRE Safety. Also, to many RVers tend to overload their RV’s and don’t realize it.

    RV manufacturers usually put on the cheapest tires they can get their hands on. Some don’t even check the year of manufacture, just that they have a stockpile of Tires, so get rid of them. Manufacturers do very little when it comes to safety. Tires are something all RVers need to check before buying or driving off the dealers lot. If the tires on a NEW RV are 5 years or more hold. Have the dealer replace them with new, or walk away!

    Many RVers don’t realize they need to have a 20 to 30 percent cushion on the tire weight loading. Many RV’s don’t even have a 10 percent cushion, which is very dangerous when going down the road.

    Also, buy a TPMS for your RIG. I have a 10 tire system on mine and it is the best $500 I have ever spent. A TPMS will keep you informed what is going on with your Trailer Tires and with your Tow Vehicle as well.

    BE {bleeped} ABOUT YOUR TIRES. Learn the signs of potential Tire Failure!

  4. Roger,

    this brings up an interesting companion concern: What risk is there when LEVELING (not traveling) to use only one leveling ramp?

    Yes, it’s a 100% overload, but it’s static. Is this a case of “use caution”, or “never do this”? The reason for asking is that in smaller motorhomes, carrying four leveling ramps is impractical.


    • I have a smaller (24′) Class-C myself. I carry 3 ramps. This would allow me to support both of my rear duals with two and have one extra for the front. I haven’t run into a situation where I couldn’t get “level enough” to have my refrig within the 1 bubble range on the bulls-eye level I use. Yes you might need 4 if the rear was that low but if carrying 4 ramps is a problem I would suggest you need to find a more level location.
      While the 100% load is static and isn’t likely to do any damage it is imperative that any ramp system you use is both wide enough and long enough to support 100% of the contact area of the tire. On my RV Tire Blog I have some pictures to help you understand the area that needs to be supported.

  5. I had this happen to me in Nevada, miles from any service. I had to drive about 90 miles at 30 MPH. I had no choice but to replace both tires because I could not get the original size. I got around the problem of not being able to change all the tires due to the dealer only having two. I took the front tires and had them put on the rear and put the new tires on the front. I kept the tire that had carried the load alone on the top as a spare until I got home. Then I changed out the rear tires so that all were the same. I discovered that the other side inner rear tire was close to failing. It was the inner tire that failed in Nevada.


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