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 RVtiresafety.net.