One tire fails. What about it's "mate"?

Had a question from a friend about replacing both tires when one failed on the same side of the RV. 

 In Motorhomes with "Dual" tires (side by side) in the rear and you do not get the early warning from TPMS of air loss, you need to seriously consider replacing the "un-failed tire" because when it's "mate" failed the un-failed tire was overloaded by 100% for some unknown number of miles. 
You can always take the un-failed tire to a dealer, for that brand of tire, and have it inspected inside & out, and if ruled OK, in writing, by the dealer, you could keep the tire as a spare.
However, if it ran some unknown number of miles at 100% overload, I would not even trust it as a spare. 

 Now in the case of a multi-axle RV trailer (tandem axle) and one tire failed and again you were not running a TPMS to get an advanced warning, we need to consider what happened to the load on that side of the trailer. Wouldn't all the load from that end of the axle with the failed tire transfer to the un-failed tire on that side of the trailer? This transfer would be transferred through the springs and the link between the axles. The load supported by the "failed" tire doesn't simply evaporate, does it? It has to be taken up by the un-failed tire on that side of the trailer.

So again that tire should be removed, inspected, and replaced as with the Motorhome example. It might be OK to keep as an emergency spare but only used with great caution and only if inspected and judged OK by a dealer of that brand of tire.


This is one of the things people do not think of when considering running TPMS. If you get advance warning of air loss in one tire in a "Dual" or "Tandem" location you not only might save the cost of the punctured tire if it was caught soon enough to be repaired but you might even have saved enough by not losing the 2nd tire not to mention avoiding the $Thousands of possible damage to the RV.

 ##RVT959 

When to replace tires? Can you drive on one "dual"?

Was reading a magazine aimed at motorhome owners and there was an item about a man that suffered a 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 life.

The magazine did offer a brief explanation on how to "read" a tire DOT serial and learn it's age.

IMO the magazine missed an opportunity to further educate their 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 over 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

BOTTOM LINE
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.


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##RVT820