Tire pressure

[fjr vfr]

My trailer lists pressure at 65 psi for the 225/75-15 load range D tires that come with the trailer.
These tires were replaced with load range E tires of the same size. Load range E tires are rated to run at 80 psi
I weighed my trailer and have just under 8,000 lbs on the axles and 1,800 lbs pin weight.
Looking at Maxxis load and inflation tables they show 45 psi at 2,020 lbs per tire.
I don't plan on running below the 65 psi listed for the original tires, I think 45 psi is too low, but I am now running a stiffer tire, so should I be running at a higher psi than 65? I think 80 psi would be too hard for the weight.


I know many people go to a higher load range tires, so I wonder about other opinions?


Thanks

[sourdough]

I went from the same tire you had to the same E rated tires. My trailer is 10k gvw and runs about 9200 or so. I run my trailer tires at 80 psi and completely disregard the "tongue/pin weight". That is an ideal number but when you are driving down the road hitting frost heaves, pot holes, dips, jumps....each of those tires isn't carrying the "ideal" load. In many, if not most, they are way overloaded in some of those scenarios. As far as rougher ride, I've never seen it. Since going to the E tires vs the D tires my trailer actually rides better and nothing moves inside any longer. JMO/YMMV

[Genek]

Originally Posted by sourdough

I went from the same tire you had to the same E rated tires. My trailer is 10k gvw and runs about 9200 or so. I run my trailer tires at 80 psi and completely disregard the "tongue/pin weight". That is an ideal number but when you are driving down the road hitting frost heaves, pot holes, dips, jumps....each of those tires isn't carrying the "ideal" load. In many, if not most, they are way overloaded in some of those scenarios. As far as rougher ride, I've never seen it. Since going to the E tires vs the D tires my trailer actually rides better and nothing moves inside any longer. JMO/YMMV

Over or under pressure for your weight will cause improper wear of the tire. That’s the real issue with pressure rather than ride. We all know what a blow out costs us in damage to the trailer.

[sourdough]

Originally Posted by Genek

Over or under pressure for your weight will cause improper wear of the tire. That’s the real issue with pressure rather than ride. We all know what a blow out costs us in damage to the trailer.

I agree. Ride is probably irrelevant in any conversation regarding trailer tires. As far as "improper wear", I've never owned a trailer tire that I didn't get rid of while it still looked brand new....never know...

[Wing-in-it]

I always run 80 psi. Low tire pressure creates heat.... Heat is bad.

JMHO.....

[notanlines]

It would be my opinion at the tires should run at 80 PSI like Danny suggested. I can't back that up with manufacturers informational data, but when you went up from a D to an E I believe the best scenario is 80 PSI.

[JRTJH]

225 80R15 LRD tires at 65PSI are rated to carry 2540 pounds
225 80R15 LRE tires at 65PSI are also rated to carry 2540 pounds and at 80PSI are rated to carry 2830 pounds.

Why go to the expense of buying "increased load tires" and then run them at reduced pressure and lose that extra capacity. There's "nothing extra" and no "increased protection" when you run LRE tires at LRD pressures.

Sort of like going on a diet, then buying snack food to put in the refrigerator, knowing that you won't eat it and watching it go bad on the shelf while not using it.

[jadatis]

Originally Posted by JRTJH

225 80R15 LRD tires at 65PSI are rated to carry 2540 pounds
225 80R15 LRE tires at 65PSI are also rated to carry 2540 pounds and at 80PSI are rated to carry 2830 pounds.

Why go to the expense of buying "increased load tires" and then run them at reduced pressure and lose that extra capacity. There's "nothing extra" and no "increased protection" when you run LRE tires at LRD pressures.

Sort of like going on a diet, then buying snack food to put in the refrigerator, knowing that you won't eat it and watching it go bad on the shelf while not using it.

Used the tirespecifications you gave and added 10% to the2020lbs topicstarter gave.
Then the 65psi tire would need 55psi , I calculated with the safer official European formula, ( I once got hold of, and went running with.
That they give 65 psi is general advice for trailers.
Most trailer tires are ST wich are calculated in maxload for 65mh. This gives no reserve anymore for things like unequall weight, pressure loss, etc.
Thats the reason for that standard advice of 65 psi for D-load. E- load would need 70 psi for the 2540lbs maxload of D-load.
But if you are shure of the 2020 lbs a tire as you weighed( and I added 10% to cover unequall weight R/L) , the E load would need 60 psi.

When I calculate advice for trailers, I add 10% and lower maxload, as if its a Q speedrated tire, wich is calculated in maxload for 99mh.
Then you have the highest pressure, with max reserve, with still acceptable comfort and gripp.
Comfort for a traveltrailer, is that your screws wont tremble loose from the woodconstruction.

Can do that for you, but need more information.
fi if you have ST and if weighing was fully loaded.
Number of tires and axles.

[JRTJH]

Originally Posted by jadatis

Used the tirespecifications you gave and added 10% to the2020lbs topicstarter gave.
Then the 65psi tire would need 55psi , I calculated with the safer official European formula, ( I once got hold of, and went running with.
That they give 65 psi is general advice for trailers.
Most trailer tires are ST wich are calculated in maxload for 65mh. This gives no reserve anymore for things like unequall weight, pressure loss, etc.
Thats the reason for that standard advice of 65 psi for D-load. E- load would need 70 psi for the 2540lbs maxload of D-load.
But if you are shure of the 2020 lbs a tire as you weighed( and I added 10% to cover unequall weight R/L) , the E load would need 60 psi.

When I calculate advice for trailers, I add 10% and lower maxload, as if its a Q speedrated tire, wich is calculated in maxload for 99mh.
Then you have the highest pressure, with max reserve, with still acceptable comfort and gripp.
Comfort for a traveltrailer, is that your screws wont tremble loose from the woodconstruction.

Can do that for you, but need more information.
fi if you have ST and if weighing was fully loaded.
Number of tires and axles.

Let's use a little "Cajun logic" and relate it to tire pressure. I don't go to the bank and withdraw $200 and toss $20 in the trash can on the way out the door. I don't go to Burger King, order two Whoppers and toss one in the trash on the way to the table, I don't buy tires with a specific rating and try to find ways to not use them fully.... If the tire is rated at 2400 lbs at 65PSI and 2800 pounds at 80 PSI, why toss that extra protection (weight carrying capacity) in the trash before hitching up the trailer???? Now, if that extra pressure was going to cause damage to the trailer, yes, I'd consider that aspect, but so far, NOBODY has ever documented to me that there is trailer damage incurred when running LRE tires at 80 PSI on a trailer suspension that was delivered from the factory with LRD tires rated at 65 PSI...... YMMV

[BrentB]

For what its worth I have the same size and brand tires as you. Three of them are load range d and one is load range e. (I had to replace 1 and LRE was all that was available.) I run all 4 at 65 psi, and the tire pressure monitoring system shows similar temperatures for all 4. If any of them were under-inflated, it would over-heat.

[flybouy]

This has been debated ad nauseum on this forum. Do a search and you will go blind with all the reading. One omission I note is what are your wheels rated for? Check that the wheels can take the increase pressure.

[ctbruce]

John sums it up best. If you pay for E's, use them as E's. Otherwise save the money and stick with D's.

[mazboy]

keep it simple. 'E' rated....80psi

[travelin texans]

Originally Posted by mazboy

keep it simple. 'E' rated....80psi

Provided the wheels are rated high enough, that would my 1st check (stamped on rear side of the wheel somewhere) before going to 80 psi.

[fjr vfr]

Originally Posted by travelin texans

Provided the wheels are rated high enough, that would my 1st check (stamped on rear side of the wheel somewhere) before going to 80 psi.

From what I read the wheels are rated by weight and not pressure. I also found out while researching TPMS systems the valve stems are rated by pressure and the stems in my wheels are rated at 65 psi. I've made an appointment to replace them with the proper stems.


Most all the responses are what I expected. Since they would be stiffer than D rated tires, I would think they would flex less at 65 psi than the D rated tires do? I'm thinking Keystone planed on 65 psi to allow for higher loads on individual tires over varying conditions. Since the trailer manufactures just meet the minimum they went with D rated tires to save on cost. If they had installed E rated tires maybe they would have still listed inflation at 65 psi?

If you relate it to your car or truck they all run at something lower than the tires max rating. My truck calls for 55 psi in front and 70 psi in the rear for example. But with that said, I may just run them at 80 psi? Maybe I shouldn't overthink it? I appreciate the input. I have till after Christmas when we leave too snowbird to decide.
Thanks

[sourdough]

Yes, the E tires are stiffer than Ds thankfully. Think about it this way; my trailer gvw is 10k, tires were d rated at 2540 each giving me a cushion of only 40 lbs per tire over gvw at max inflation of 65 psi. I do not consider weights by removing the tongue/pin weight; sort of like the TV "max tow" rating...pretty much meaningless to me since 1) the tongue/pin is going to vary and 2) 1/2 the time you are on the highway that weight is being transferred to the trailer/trailer tires so the "ideal" weight that the manufacturer straps you with is just idealistic IMO.

Your trailer is apparently running considerably heavier than mine and I wouldn't for one second think I could bet by on a D rated tire - especially after seeing the damage they can do in about 10 seconds when they disintegrate.

Do the E rated tires flex less than the D? I think so. Is that bad? No, not at all. In fact, it is probably a good thing. Yes, the manufacturers give you the VERY minimum to get by the LOWEST possible rating they can come up with, which, in real life is generally well below what you should have and in many dangerous IMO (as in my case).

Some wheels have the psi stamped on them, some the weight. The psi will correspond to the weight for whatever weight rating the max tire has. Mine was stamped with the weight, we put in new valve stems when the tires were installed.

Yes, you should run the new E rated tires at 80psi if the wheel allows; I would not do anything less, especially at your weight. And yes, you are overthinking it. Just get the E tires, inflate them to 80psi and get some peace of mind....beats the heck out of sitting on the side of the road with a tire carcass wrapped around your axle, your wheel well torn up, gas lines cut into and underbelly all cut up....in the middle of nowhere. And, btw, the inflation pressures recommended on my truck are 80 psi rear (max inflation) and 65 front. Don't overthink it....let logic, and safety, be your guide.

[Ken / Claudia]

Tires are different for the RV vs tow vehicle or passenger car. I adjust the psi in the rear truck tires depending on the load. Some do that, nowdays with the factory TPMS some do not adjust them. RV tires stay at the max psi the tire has printed on them.
Regarding the rv tires, I changed brands and from d to e and from 65 to 80 psi. No noticed change in bounce or tracking/towing. Maybe if you rode in the RV you might find differences. For me it is just a added safety factor. As others have mentioned.
I firmly believe the RV tires get a lot more abuse then many realize and unless your reading through the RV forms about tires many do not inspect or check them as they need. Tires/wheels/bearing real important and not given the same inspection as many other parts of the RV especially for the new RVer.

[fjr vfr]

Thanks for the input.

[Tireman9]

You have a few different things to consider.
GAWR is not based just on the tires. All other components such as springs, shackles, brackets welded to the frame and even the strength of the frame where brackets are welded on are considered by the RV MFG. Changing one or even a couple components does not increase the strength of the other components.


As a tire engineer, I will focus on the change in tire load range and tire inflation pressure requirements.
1. It is the air pressure, not the tire that supports the load so just changing the tire load range does not increase the load capacity.
2. In Trailer application better tire life (reducing the chance of a belt separation) can be achieved with an increase in inflation up to the inflation number molded on the tire sidewall.
3. You need to confirm that no single tire has been overloaded. This means get each tire on a scale. you may need to search for a location where this can be done as not all truck scales allow this. Also get the weight with the trailer at its heaviest.


More later

[BadmanRick]

If the tires say 80psi on them you run 80psi. It will be a very expensive mistake to run less when the tire blows from too much heat and flexing.