Thursday, November 30, 2023


Are you smarter than your RV tire salesperson? You may need to be

RV Tire Safety
with RV tire expert Roger Marble

With the Michelin LTX tire, you may need to be smarter than your RV tire salesperson.

As an RV owner, I believe that in most cases it is important for us to know as much as possible about our tires. Sometimes this means knowing more about our tires than the average salesperson. Here is a real-life example:

An owner of an older travel trailer posted on a forum:

“Please correct me if I’m wrong. The Michelin Defender LTX M/S 235/75R15 is a true LT tire and does not need to be derated? Shopping for tires on my Airstream 2017 23FB. I’d love to just go with the 16″ SenDel S02/Michelin combo but not sure if the clearance is there for them.”

Just before the above post it had been pointed out the correct designation is P235/75R15 XL. The “XL” is the tip-off as that stands for “Extra Load,” which is only found in passenger-type tires.

LT tires have Load Range C, D, and E. P-type have Standard Load (no special marking), and XL, which is lower in inflation than an LT-C.

Your tire dealer should have made clear the type tire they are talking about. Sometimes RV owners need to know more than the salesman if you want to get the tire you need or want.

I had also previously posted on that thread:

“Be sure you understand if your LTX tires are ‘LT’ type or ‘P’ type. If P, you need to calculate the actual tire capacity when used on trailer, SUV or pickup truck. The adjustment is: (Load molded on tire)/1.10 = Load capacity on the RV, truck or SUV application.

No load capacity adjustment is needed for LT-type tires if placed on an RV, truck or SUV. The LT in ‘LTX’ does not make a tire an actual ‘LT-type’ tire.”

I don’t know if the marketing folks at Michelin realized the confusion they were spreading when they came up with the name “LTX” and put that designation on both LT-type and P-type tires. I would not be surprised if there aren’t a good number of RV owners who think they have an LT tire when what they were sold was actually a passenger-type tire.

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



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