Can you change tire size on your RV?

There seems to be a bit of confusion when it comes to selecting tires to replace the size/type that came as Original Equipment on your RV. What you can do and what you should do are not always the same thing.

Here are some statements collected and posted by a knowledgeable person who frequently responds to questions on some RV Forums.

"Goodyear: Never fit tires to a vehicle that have less load carrying capacity than required by the Original Equipment Manufacturer.

Michelin: Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Cooper: The new tires must have a load carrying capacity equal to or greater than the maximum load carrying capacity specified on the tire placard on the vehicle.

Toyo: Any replacement tire must be of a size and load range that will offer equal or higher load carrying capacity compared to the original equipment (OE) tire on the vehicle."

I am not aware of any "legal" requirement that specifies what the RV owner is required to do. While it is a legal requirement from DOT that the vehicle manufacturer must select and specify tires and the inflation necessary to support the stated Gross Axle Weight Rating, as far as I know, this legal requirement does not apply to individual owners of vehicles.

HOWEVER, I doubt that you will find any company or responsible individual willing to state that it is good practice to select replacement tires that do not have a stated load capacity that is equal to or greater than the load capacity of the original tires.

All tires sold for use on public highways have a stated maximum load capacity at a given inflation pressure molded onto both sidewalls. This fact, along with the information in published Load/Inflation tables, makes it relatively easy to find tires with the needed load capacity.

There are a number of reasons to consider an alternate size tire (availability, cost, brand reputation, etc.) but in every case you should only select new tires that can support at least as much load as the OE tires.

The above is based on an assumption that the load on your tires is split equally 50/50 side to side on each axle. Since this is seldom the case, this is an extra bit of information you should consider when shopping for new tires.

I have numerous posts on this blog where I outline the importance of confirming the actual load on each end of each axle. This is because it is possible to have the load unbalanced to the point that one tire may be overloaded even if the total tire load capacity for all the tires on an axle numerically exceeds the total axle load measured on a truck scale.

When should you replace your tires?

Saw the following question on an RV forum from a motorhome owner.
"Does anyone ever just replace their front tires after 7 years? It seems that a tire failure on the front is much worse than the back. If the tires have a lot of tread and no sign of cracking, why replace the back ones?"

One reply correctly said, "There's more to consider than age. Were they properly inflated? Did you bang into curbs to damage the sidewalls? There are many failures due to improper operating conditions. Not just age."

I would first ask if you know the "life experience" of the tires:

Did the RV have a previous owner?
While they may claim they always checked inflation, can we be 100% certain?
Did you purchase the tires direct from a major tire company and know the complete use history?
Have you confirmed your load on all the tires from day one?
Did you ever discover one of your tires 20 or 30 psi low one time?

There are many things to consider, but if you are confident the tires have always been properly inflated for the actual load the following should help.

"Blowouts" (look at the picture at the top of my page), or more properly Run Low Sidewall Flex failures, happen because of running on low inflation. This can be avoided with the use of TPMS.

Belt separations, which are much less common on commercial grade tires, may occur after the rubber at the belt edges degrades due to cumulative damage from heat.

UV does not affect the internal structure of tires and external cracking is only one symptom of exposure to sunlight. I consider external cracking like having a person run a temperature. Having a temperature is just a symptom of some other illness, usually an infection. You can be seriously ill but not be running a temperature. Think of heart disease or cancer as two things that can kill you but don't cause you to run a temperature.

The suggestion on when to replace tires is only based on probability, as it is impossible to know just how much damage has been done to the components of a tire. The general suggestion is to have tires closely examined by a tire expert at 5 years and each year after that. Tires should be replaced at 10 years no matter what is visible on the surface of a tire.

I wrote a blog post on a suggested inspection and "step replacement" concept. A version of this suggestion could result in your keeping newer tires on the front, which in theory should improve your chances of not having a belt separation on the front. Of course also running TPMS will improve your chances of not having a Run Low Flex Failure too.

##RVT803

Soften the blow to your wallet when buying tires

Recently read a blog post about the "sticker shock" of the cost of "truck type" tires for the large RV. I would like to offer a suggestion on how to soften the financial hit. This strategy can work for all RVs be they trailers, Class-B, Class-C or Class-A size units.

It a simple plan and will only take a few minutes to lay-out. With the planning behind us we will be prepared to take advantage of any special deals or short term sales we might come across.

Now to follow this plan there are a few bits of  information you need to have:

You need to know the exact size, Load-Range and DOT serial date for your current tires.
Sorry but just thinking you have 235-16 size tires that you bought in 2009 doesn't cut the mustard.

If you are not sure how to get this information I suggest a quick refresher is in order so you might read the post on "Reading a Tire". So lets assume you have collected the details on your tires so you know exactly what you will be looking for over the next few months.

Here is how my suggestion works.
If all your tires are the same size I would suggest you plan on replacing the two oldest tires first. The new tires would go on the front positions and the others in dual position in the back.

Next year I would buy two more new tires, place them on the front and move the tires that were on the front back to one pair of duals.

Then the third year buy two more tires, place them on the front position and move the older fronts back to the rear.

The above schedule serves a few purposes:

1. It spreads out the purchase over a three year period.
2. It has you running on the newest tires on your front position.
3. With this plan you can spend months shopping for the best deal and avoids the need to accept tires that may be years old before you even buy them. Since you know you have a plan and you know that over a six to 10 month time period to do your shopping.
4. When you are done you know your oldest tires are three years old and if you plan on changing tires when they get to seven or eight years you now have a four year period to set aside some cash for when you start the cycle over again. You can continue this schedule for as long as you own your RV and never be confronted with having to buy more than two tires in any year.


Now if your fronts are different size than your rears as seen on some large Class-A units you can't do the front tire rotation but you can still limit the purchase of your rears to just two a year

With a little planning no one should have to buy more than two tires in any one year. It just takes some thought and planning.



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