Miss matched load range tires

[Bob K4TAX]

Our 2016 Wildwood X-Lite 253RLXL came with load range C tires. These were rated a 1760 lbs @ 55 psi. The GVRW of the trailer is 7685 lbs. Thus 1760 x 4 = 7040.

The point is the original tires were not adequately rated for the GVRW of the trailer. But that is the way it came from Forest River. I suppose if one subtracts the tongue weight of about 700 lbs, they just make it with little to spare.

We upgraded to load range D rated at 2040 lbs at 65 psi. Thus 2040 x 4 - 8160.

We feel more comfortable with these tires on the trailer.

Bob

[jadatis]

Answer to post #21

Filled in the C- load in my made extra safe calculator, and gave 54psi advice, because I add standard 11% to the load on tires to make them use 90% of the loadcapacity for the calculated pressure.
Even did not lower the loadindex, so this proves that the C- load have poor reserve, even to american 10% reserve standards.
And that is to the GAWR, and those could be higher then (7685-10%) /2, try to find that too.

Then the D-load 2040lbs AT 65psi.
My calculator gives 61psi, yes higher then for C load 54psi.
So you would think enaugh reserve now.

But to my pigheaded standards, the tire gives maximum reserve, with still no screws trembling loose, if 90% used of loadcapacity for 99mph.
ST tires are given maxload for 65mph, so I lower maxload by 6 loadindex steps to give the tires a deflection for 99mph needed.
That filled in gave advice of 74psi for your new D-loads

So at least keep them on 65psi, and certainly dont use the old 50psi advice.

So FR is a brand that goes to the edges wirh tires and probably also with GAWR's.

On the Airstream forum I discovered that Airstream does it better.
First comfortable reserve in the GAWR('s) to the GVWR, and second comfortable reserve in the tires maxload to that comfortable GAWR.
Then If I calculate for max reserve, it still stays below the referencepressure of C-load AT 50psi, and D-load AT 65psi E 80psi.

Mayby others here want to give their specifications, so I can do the same calcs.

So to get on topic again, can be that TS D-load even have poor reserves, and even better to switch to E-load, and mayby even have to use the full 80psi then.

You cant demand this from your dealer, but mayby you can take this in your nacociations.

[teddy]

This may be a dumb question. I have Goodyear Endurance tires size st205/75sr14. They are load range D.
I've read many writers say they upgrade to load range E. I have always been confused because doing so requires a different tire size. My question: does the tire size matter? Can I put a different size tire on the same rims?
Thanks. And sorry for hijacking the thread.

[Oaklevel]

Originally Posted by teddy

This may be a dumb question. I have Goodyear Endurance tires size st205/75sr14. They are load range D.
I've read many writers say they upgrade to load range E. I have always been confused because doing so requires a different tire size. My question: does the tire size matter? Can I put a different size tire on the same rims?
Thanks. And sorry for hijacking the thread.

Maybe, it depends on the tire size difference and the rims.

[wmtire]

Originally Posted by teddy

This may be a dumb question. I have Goodyear Endurance tires size st205/75sr14. They are load range D.
I've read many writers say they upgrade to load range E. I have always been confused because doing so requires a different tire size. My question: does the tire size matter? Can I put a different size tire on the same rims?
Thanks. And sorry for hijacking the thread.

There are 3 parts to a tire size. Using your example of 205/75R14.

The 205 is the section width in millimeters (205 millimeters wide)
The 75 is the aspect ratio (which means the sidewall is 75% of the section width)
The 14 is the rim diameter in inches (14 inches)

So you can put a different size tire (Example 215/75R14) on the 14 inch rim as long as the last number is 14. If the number is anything else (ex 13, 15, 16,), then you have to change the rims.

Now changing the load range doesn't necessarily mean changing the tire size. Say for example you had a 205/75R15 Load Range C. You could change to a Load Range D, E, F and keep it all the same except for the amount of load the tire can carry

There are a lot more options in Load Ranges though in 15-16 inch rim diameters, than there are in 13-14 inch rim diameters..

[Airdale]

Originally Posted by teddy

This may be a dumb question. I have Goodyear Endurance tires size st205/75sr14. They are load range D.
I've read many writers say they upgrade to load range E. I have always been confused because doing so requires a different tire size. My question: does the tire size matter? Can I put a different size tire on the same rims?
Thanks. And sorry for hijacking the thread.

Yes, tire size is very important when considering "plus sizing". RV trailer manufacturers are notorious for building their units very close to tolerances. Sometimes just an inch of extra tire height will hamper safety. With dual or triple axel trailers the trailer builder may have a tire's designated size in mind and close the gap between axles to the point where a larger tire size will not comply with safety standards and may very well be unsafe to do. Extra width can hamper suspension operations.

With tires having enough load capacity to provide a reasonable load capacity reserve, there is really no valid reason to plus size. My bet is the vehicle manufacturer will not recommend plus sized tires as long as the OE tires have sufficient load capacities.

Note: A tire's designated size does not change when using available increased load ranges. They are not part of a tire's size.

[teddy]

Thank you all for your replies. I think wmtire hit the nail on the head. "There are a lot more options in Load Ranges though in 15-16 inch rim diameters, than there are in 13-14 inch rim diameters."
Also as per Airdale, I think I have plenty of load reserve, no need to upgrade.


Thought I'd mention... I drove across country twice and to Alaska from New York with "China bombs." I never had a problem. I switched to Goodyear's and had a blowout the first day out. It appeared that something sliced through the sidewall. Probably no tire would survive that. But how ironic is that?

[dward51]

Originally Posted by teddy

I drove across country twice and to Alaska from New York with "China bombs." I never had a problem. I switched to Goodyear's and had a blowout the first day out. It appeared that something sliced through the sidewall. Probably no tire would survive that. But how ironic is that?

That is why they offer "road hazard" insurance at most tire dealers. Sometimes it's just a bad day, and you did everything right, but...

Also a plus for buying tires from a national chain with dealers pretty much everywhere to cover it.

[NMWildcat]

Originally Posted by dward51

That is why they offer "road hazard" insurance at most tire dealers. Sometimes it's just a bad day, and you did everything right, but...

Also a plus for buying tires from a national chain with dealers pretty much everywhere to cover it.

Most places around here will not sell road hazard for trailer tires.

[wmtire]

Originally Posted by NMWildcat

Most places around here will not sell road hazard for trailer tires.

It depends a lot. Many times "road hazard" is offered and/or self insured by the dealer. This is why you see it at some cheaper prices from the national tire places. Independent shops (like moi) can purchase it from places that do sell this type of insurance on a per tire basis, but it can be higher costs.


Now the company I use for road hazard does specifically exclude trailer tires, but this can be all over the board with the big national places. Some exclude them, some don't, some it's a mixture. Always read the road hazard policy and look for key exclusions that can be hidden like "specialty use tires" etc.


Now just to really muddy up the waters, there are actually a few ST manufacturers themselves that will put a very limited use/time road hazard on their products. Like this one below:


https://triangletireus.com/wp-conten...8x9-FOLDED.pdf

[Tireman9]

Originally Posted by Bob K4TAX

Our 2016 Wildwood X-Lite 253RLXL came with load range C tires. These were rated a 1760 lbs @ 55 psi. The GVRW of the trailer is 7685 lbs. Thus 1760 x 4 = 7040.
The point is the original tires were not adequately rated for the GVRW of the trailer. But that is the way it came from Forest River. I suppose if one subtracts the tongue weight of about 700 lbs, they just make it with little to spare.
We upgraded to load range D rated at 2040 lbs at 65 psi. Thus 2040 x 4 - 8160.
We feel more comfortable with these tires on the trailer.
Bob

Tire loading is based on GAWR not GVWR - hitch.


There is a certification sticker on the RV saying what size & Load Range and inflation to run in the tires.

[Bob K4TAX]

Originally Posted by Tireman9

Tire loading is based on GAWR not GVWR - hitch.


There is a certification sticker on the RV saying what size & Load Range and inflation to run in the tires.

Based on the RV Tire Safety link:
"So, when shopping for tires you should start off by knowing the “Complete” Size Designation which includes all the numbers and letters from your Original Equipment tires such as “LT235/75R16 114 / 117 L LR-E “. Most, if not all, of this information, can be found on your RV Certification Placard or “Sticker”.

If you are going to change any of the above numbers or letters on your tires when buying replacements, be sure the new tires are rated equal or higher for all the Load, Inflation, and Speed symbols. You should never go to a lower load capacity with new tires. In the original example, the new tires are XL and 108, which means higher inflation and higher load capacity."