Trailer Tire Question

[harry_and_thea]

We have a 2014 Rockwood Signature Ultra Light 8244WS fifth wheel, 26 ft 9 in long with a dry weight of 6537 Lbs and probably 7500 lbs loaded. Was on a trip in Northern Ontario last month when I noticed a strange gouge in one of the stock tires. Put on the spare and stopped in the first town with a tire dealer for a replacement.
Stock tires are ST 225/75R15 Trail Express Power Towing made in China load range C with max load 2150 @ 50 psi.
Dealer recommended replacement tire same size Good Year Endurance load range E made in USA max load 2830 @ 80 psi. He said it was absolutely ok to run the new tire at 50 psi along with the remaining 3 original tires. I have been a little uneasy about the underinflation of this tire.

My stock tires are now exactly 5 years old from date of manufacture. So I am considering replacing the remaining 3 tires. I definitely want to upgrade to a higher load range but don't want to run 80 psi for harshness of ride.
If I bought 3 identical tires to the one I replaced and ran them at 65 psi, would that be a good idea? Or would it be better to buy four new load range D at 65 psi and replace the spare with the one bought up north.

I guess the real question here is if it is ok to run a heavier load range E tire at a lower pressure providing you don't have the weight or is it preferable to go to maximum pressure with load range D

Would sure appreciate input from those with tire knowledge.

[laknox]

First off, check the PSI/load rating for your wheels before you so putting on higher-rated tires. Even with a D tire, you may find that the wheels are only rated for a C pressure/load. Personally, I think an E tire on your rig is =way= overkill and a D will likely serve you well. If you =do= go with an E, there's certainly no need to put 80 psi rated wheels on, as you're likely never going to want to exceed 65 psi on those tires anyway. Also, given GY's recent track record on trailer tires (excepting the G-rated stuff), I'd not be in a rush to jump on the Endurance band wagon without a lot more miles and reports on them from those who are using them. Carlisle had a bad rep for years, but the last few years have really upgraded their tires and I'd put another set on my FW without hesitation. I'm running the older RH E's and have had zero problems with them. I do run at 80 psi though I'm placarded for D tires, unless I'm running light, then I'll drop to 70. Just my $0.02...

Lyle

[JIMNLIN]

I will go with what Goodyear says rather than what someone posted on the internet!!!!!

Well according Goodyears RV website "weighing RVs" they say;

Goodyear Tire and Rubber .... weighing RVs
Special Considerations

**Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up.**

And if your using Carlisle ST tire then their warranty says;

Carlisle ST tire warranty;
-Maintain air pressure at the maximum PSI recommended on the tire sidewall.
-The Warranty is void if the tire or wheel fails due to damage from improper inflation pressures, exceeding the maximum speed limit, or overloading the tire beyond the maximum load capacity stated on the sidewall


However for those that over tire their trailer I've found this works best in that situation;

rvsafety.com
Tire Load and Inflation Ratings

Note: Towable – Travel Trailer/ 5th Wheel owners Due to the severe use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.**

[time2roll]

harry and thea wrote:
Thanks to Down the Avenue
That chart is just what I needed. I will buy three more Endurance E and inflate to 60 to 65 which is max for my rims and have lots of reserve. According to that chart by Good Year it is ok to inflate below the max depending on load.

Yes if the wheels are specifically limited to 65 psi that would be the pressure limit.
Does the wheel have a weight limit too?

[Cummins12V98]

Go up one load range. Run the "D" tires the same pressure plus 5psi as the "C" tires as you most likely were running at full load range. Best bet is to weigh the tires and use load/inflation chart and add 5psi this is per GY Tech Support.

Just installed the GY Endurance on my 23' GlasPly boat trailer. Went from "C" to "D", funny the tires don't look flat any longer!

[MFL]

One other point...this is a smaller FW, that OP is guessing will weigh 7,500 lbs loaded. Using that number, figuring 20 percent pin wt of 1,500 lbs, leaves only 6,000 lbs on the 4 tires. That is how the manufacturer gets by with the C-rated OEM tires. Now if you put the D-rated on, at 2,540 each, inflated to max 65 lbs, your good to 10,160 lbs, and likely within wheel specs. If OP wants to go to E-rated, and inflate to 50-65, his choice, but I would not.

Jerry

[mapguy]

harry and thea wrote:
Thanks to Down the Avenue
That chart is just what I needed. I will buy three more Endurance E and inflate to 60 to 65 which is max for my rims and have lots of reserve. According to that chart by Good Year it is ok to inflate below the max depending on load.

Load and Inflation chart derived tire inflation pressures depend on factual data to be successful. Have you actually put the trailer on a scale to know the actual weights involved? Not uncommon for RV's to have grossly different tire loads, especially units that have slide-outs.

[harry_and_thea]

Thanks to Down the Avenue
That chart is just what I needed. I will buy three more Endurance E and inflate to 60 to 65 which is max for my rims and have lots of reserve. According to that chart by Good Year it is ok to inflate below the max depending on load.

[DownTheAvenue]

JIMNLIN wrote:

Dealer recommended replacement tire same size Good Year Endurance load range E made in USA max load 2830 @ 80 psi. He said it was absolutely ok to run the new tire at 50 psi along with the remaining 3 original tires. I have been a little uneasy about the underinflation of this tire.

You should well feel uneasy.
This speaks volumes about this dealers experience with tires on trailers. Lawn service trailers don't count.
A dealer with experience in the trailer field would know better than to make a rookie recommendation such as running a 80 psi tire at 50 psi. There is nothing gained by derating the E tire to 50 psi according to this tire engineer . Read his blog on http://www.rvtiresafety.net/2013/10/will-you-increase-load-capacity-with.html. Spend some time on his blog.....lots to learn from a actual tire engineer.

Your 7500 lb loaded trailer doesn't tell us your OEM tire size and load range or your trailers axle ratings.

A 7500 lb trailer = approx 1875 lb per tire. Now add a good 10-20 percent reserve = around 2200-2300 lbs per tire.

Your math is correct and your margins for reserve are good. Using Goodyear's tire inflation chart and the tire size on the OP's trailer, he should inflate his tires to 50!!!!!

I will go with what Goodyear says rather than what someone posted on the internet!!!!!

[DownTheAvenue]

harry and thea wrote:
We have a 2014 Rockwood Signature Ultra Light 8244WS fifth wheel, 26 ft 9 in long with a dry weight of 6537 Lbs and probably 7500 lbs loaded. Was on a trip in Northern Ontario last month when I noticed a strange gouge in one of the stock tires. Put on the spare and stopped in the first town with a tire dealer for a replacement.
Stock tires are ST 225/75R15 Trail Express Power Towing made in China load range C with max load 2150 @ 50 psi.
Dealer recommended replacement tire same size Good Year Endurance load range E made in USA max load 2830 @ 80 psi. He said it was absolutely ok to run the new tire at 50 psi along with the remaining 3 original tires. I have been a little uneasy about the underinflation of this tire.

My stock tires are now exactly 5 years old from date of manufacture. So I am considering replacing the remaining 3 tires. I definitely want to upgrade to a higher load range but don't want to run 80 psi for harshness of ride.
If I bought 3 identical tires to the one I replaced and ran them at 65 psi, would that be a good idea? Or would it be better to buy four new load range D at 65 psi and replace the spare with the one bought up north.

I guess the real question here is if it is ok to run a heavier load range E tire at a lower pressure providing you don't have the weight or is it preferable to go to maximum pressure with load range D

Would sure appreciate input from those with tire knowledge.

http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Here is Goodyear's tire inflation chart for the tire you bought.

Replace the other three with that same tire, and inflate according to this chart.

[JIMNLIN]

Dealer recommended replacement tire same size Good Year Endurance load range E made in USA max load 2830 @ 80 psi. He said it was absolutely ok to run the new tire at 50 psi along with the remaining 3 original tires. I have been a little uneasy about the underinflation of this tire.

You should well feel uneasy.
This speaks volumes about this dealers experience with tires on trailers. Lawn service trailers don't count.
A dealer with experience in the trailer field would know better than to make a rookie recommendation such as running a 80 psi tire at 50 psi. There is nothing gained by derating the E tire to 50 psi according to this tire engineer . Read his blog on http://www.rvtiresafety.net/2013/10/will-you-increase-load-capacity-with.html. Spend some time on his blog.....lots to learn from a actual tire engineer.

Your 7500 lb loaded trailer doesn't tell us your OEM tire size and load range or your trailers axle ratings.

A 7500 lb trailer = approx 1875 lb per tire. Now add a good 10-20 percent reserve = around 2200-2300 lbs per tire.

[rrupert]

Nobody has mentioned the maximum pressure rating of the wheels. I am certainly no expert in this department but wheels do have pressure ratings that should not be exceeded. Maybe someone can pick up on this.

[Road_Phantom]

I just put a set of the same on my Cougar. Max air is around 80lbs, so 50 sounds way below the recommended pressure. I would change the other three like someone suggested.

[theoldwizard1]

Letter load rating and # of ply ratings are really not the best. All tires now have the actually load rating on the sidewall.

[BuzzWolfAR]

Check with Goodyear. They will have a tire pressure that should be run based on your load. Don't guess with this, you don't want to underinflate and create a blowout.