Trailer tires pressure

The tire manufacturers know far more about their tires than the trailer "builders". The trailer builders are covering their building of trailers against boaters who are going to abuse the trailers. Over inflation will cause abnormal wear patterns. There are plenty of articles about this.

Here is the quote off the Endurance pressure chart:

LOAD/INFLATION INFORMATION FOR GOODYEAR® ENDURANCE SPECIAL TRAILER (ST) TIRES
TIRE LOAD LIMITS (LBS) AT VARIOUS COLD INFLATION PRESSURE[/u]S (PSI) USED IN NORMAL HIGHWAY SERVICE*
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The tires will go up in pressure as they heat up. The exception to this may be as one goes up in altitude a large amount.

I run temp and pressure sensors on all of the trailer tires (and have been RVs) for a very long time.

Go with what the trailer tire manufactures give as proper inflation.
 
Alain, hopefully this will load with it's formatting in tact. This is on my F150 and CD25.

Ford F150 & C-Traveler weights
1. Boat: no gas or water, no travel items. F150: Full gas, no driver/passenger
2. Boat: Full fuel and water and some food and equipment.
F150: Full fuel, driver and passenger, Kayaks and some equipment in back bed


Ford F150 Maximum Allowed With Boat 1 With Boat 2
Payload: 2001 lbs
Front Axle (GAWR Front): 3375 lbs 2860 lbs 3180 lbs
Both Axles (Total) (GVWR):7000 lbs 6140 lbs 6740 lbs
Back Axle (GAWR Rear): 3800 lbs 3280 lbs 3560 lbs
Boat Axles 6320 lbs 7660 lbs
Towed Weight: 9700 lbs 7040 lbs(8000 licensed) 8304 lbs
Tongue Weight 500 lbs(1000 lbs WDH) 615 lbs 644 lbs
Gross Combined Weight (GCWR)14400 lbs12460 lbs 14400 lbs

Ford F150 weighed 1/13/2021, full gas, no driver or passengers or cargo: 5,400 lbs.
LoadRite Trailer weighed 1/13/2021, empty, no boat. Tongue 360 lbs
Axles 1,280 lbs
Total 1, 640 lbs

C-Traveler weight, no fuel or water, no trailer: 5400 lbs.

I'd say your estimate is fairly good with out fuel and water or much loaded.
Colby
 
" The above table DOES NOT endorse the reduction of air pressure.
It is to be used as an exampleof the relationshipbetween air pressure vs,load or lack there of. Carlisle Tire & Wheel only recommends and only warrants tires maintained @ the max air pressure while in service. The above tableshows the relationship between air pressure and load capacity for popular sizes of trailer tires. The capacities apply equally to radial and bias versions, The letters following some capacities indicate the load range."

There is more after that regarding Maximum PSI,

"Maximum load range is attained only when the tire is at its maximum air pressure. There is no advantage to taking air out of the tire, With maximum pressure the tire will perform and wear better and you will get better gas mileage. Reduce the PSI and you compromise the functionality of the tire."
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
I think that pretty much sums it up. I run Carlisles at their full maximum PSI, averaging 10,000 miles a year. The only problems I've had, were on older Goodyear tires... :mrgreen:
 
colbysmith":39ovaxml said:
Do what you want....the load rating for the ST 225/75/15E is 2500 pounds per tire at 80 PSI if you're running them as a dually - single gives a couple hundred pounds more per tire. At 80 PSI and a light load they are quite jarring and accelerate wear in other components. The load rating of my 315/75/16E BFGs on my truck at 80 PSI is 3860 per tire and if you run them there, you will feel every bump in the road in my 3/4 truck and will likely suffer from kidney failure. Again....to each his own, but like it or not tire inflation is relative to load. As Dr. Bob said, go look at a chart if you're in doubt.
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I believe the single tire rating for that tire is more like 2830 lbs. I don't know of any boat trailers that run dually's. The reason for the lower load rating when running them as duals, is to keep the flexing sidewall from rubbing each other. If you can find a tire inflation guide for the tire you have, great. But it's only going to be accurate if you weigh each tire under load to get an accurate weight. Which will change every time you move stuff around in the boat, add fuel or water, etc. The simplest method really, is too just follow the advice of almost all tire shops and manufacturers to run the maximum PSI shown on the sidewall of the tire, when running ST tires. We're not talking LT or P tires, which are not made for trailers. Nor are ST tires made to be ran on passenger vehicles. In the long run, you will do more damage running an under-inflated trailer tire. But as you say, to each their own. Colby
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Never said to run underinflated tires. I said set your inflation according to the load. I agree with you - underinflated tires are not a good thing at all.
 
The wear pattern on the tire, depends on the relative air pressure. Do you run your truck tires at maximum pressure. I sure don't--I run them for the load present in the truck at that time.

Same with the RV's

If you run with overinflated tires you will have middle of the tread excessive wear. (Under inflated, then outer edges wear.

We arty a Vaire 12 compressor and adjust the pressure as necessary. Been doing this for about 60 years of trailering and RVing.
 
Bob, trailer “ST” tires are different from “LT” and “P” tires. Those passenger, truck and RV tires are meant to be run at the vehicles recommended tire pressures. Trailer “ST” tires are recommended to be ran at maximum psi shown on the tires sidewall. Several references have already been documented here supporting that. What psi did you run your 25’s trailer at? If you have other documentation offered by tire or automotive manufacturers I would be interested in reading it. In the end most folks will have to change out their 5 or 6 year old tires before they even see much of a wear pattern. :lol: Colby
 
" . . . In the end most folks will have to change out their 5 or 6 year old tires before they even see much of a wear pattern. Laughing Colby"

Well, except for Colby and maybe Jay and Jolene :wink:

Harvey
SleepyC :moon

IMGP6704.thumb.jpg
 
I talked to the folks at Goodyear today and they said run them at the max pressure. They said that when they heat up the pressure will increase 10-12 lbs above that max pressure and that was ok. They also told that what I was doing in the summer heat was ok too. They then confirmed that the life of a tire is 3 years because they only are good for half there rated capacity at that point. At 3 years my boat would be over weight for the tire capacity.
 
This has been a very worthwhile topic.
It would be great to make the final few entries "sticky" so that others may learn the correct procedure for trailer tire inflation.
 
Not trying to tell anybody what PSI to run in their tires; just sharing my experience and what I've found in researching tires. Now sharing my thought process on why I follow the max psi advice.

Consider this. LR C = 1820 lbs/tire or 3640 lbs / axle @ 50 PSI
LR D = 2540 lbs/tire or 5080 lbs/ axle @ 65 PSI
LR E = 2860 lbs/tire or 5720 lbs /axle @ 80 PSI

The only reason I can see for running a higher load range tire than what your boat trailer needs, is to offer more support for the other axle on a dual axle trailer if one wheel fails.

When I had my 22, it's weight with the trailer was 5100 lbs. If it was evenly distributed, then that meant one side of the trailer weight was 2550 lbs. The trailer originally came with LR C tires. If I were to blow or lose a tire, that meant that the other tire on that side would have to carry the full 2550 lbs. Well over the 1820 lbs rating of a LR C tire. I upgraded to a LR-D "2540lb" tire, which came very close to being able to handle the additional weight if I lost a tire. I ran 65 lbs in those tires, and didn't notice any difference in the way the trailer rode. Now on the 25, my boat can weigh up to 8400 lbs, or maybe more. That's 4200 lbs per side if weight is evenly distributed, or 2100 lbs per tire. The new trailer came with LR-D tires on it, 2540 lbs/tire. If I were to lose a tire that remaining tire would have to carry the full 4200 lbs. Best I run the max psi of 65 psi. Eventually when I replace these tires, I'll upgrade to E's. But even they are only rated at 2860/tire, so I'm still going to be under-rated if I lose one, but again I'm much better off running the max psi of 80.

FWIW, my trailer capacity plate shows ST 225/75D15D tires, with a recommended psi of 65. (Same as the max psi on the tire's sidewall.) I don't own a tomcat, but I'm betting a new tomcat trailer will show LR-E tires, with a recommended psi of 80. And a trailer capacity of 11,440 lbs. Unless a Tomcat and trailer weighs less than 9940 lbs, in which case probably back to LR D tires.

A 22 on a single axle trailer would likely need at least a tire with a load rating of D. Two tires could then support 5080 lbs, which is probably pretty close to the weight of the trailer and boat. So I would imagine that the psi on the trailer's capacity plate would show a recommended psi of 65.

I'm not sure how much heavier a galvanized trailer is over an aluminum one, but I'm guessing around 500-750 lbs maybe?

Anyway, it makes sense to me to run the max psi as shown on the tire's sidewall. Under-inflation is going to do more damage than not. And as for over inflation, I believe they are referring to over maximum on a cold tire. You will likely see an additional 5 or more psi on a running or hot tire. (I see 6-8 psi more on my F150 with "P" LR D tires set at 36psi). But the manufacturers say not to remove air in that case. All the above is in regards to an ST tire in the 15" range. By all means, follow the automobile manufacturers recommended tire pressures on your LT and P tires recommended for your Cars, trucks and RV's, as that is the setup they used to provide the best/safest ride on their products! One last observation. I didn't notice any abnormal wear on my 22 with the LR-D tires at 65 psi. Colby
 
I talked to the folks at Goodyear today and they said run them at the max pressure. They said that when they heat up the pressure will increase 10-12 lbs above that max pressure and that was ok. They also told that what I was doing in the summer heat was ok too. They then confirmed that the life of a tire is 3 years because they only are good for half there rated capacity at that point. At 3 years my boat would be over weight for the tire capacity.
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Thanks for that info Jody. I also sent emails to several of the tire manufacturers to see what their advice was. I'll share it when I get it, but suspect it'll fall in line with the advice you got. Colby
 
This reply, from Kenda Tire company:

Hello Colby,
We suggest running trailer tires at the max cold inflation pressure marked on the sidewall of your tire. For the load range of your tires that is best pressure to run them at. If you have any further questions please let me know.
Thanks,
Matthew​ White
Warranty Administrator
American Kenda Rubber Industrial Co., LTD
330-526-2658 Direct
330‑526‑2651 Main
330-494-0955 Fax

Goodyear and Trailer King just sent me a generic weight chart without any recommendations. :roll:
 
All travel trailers, camping trailers and 5th wheel RV trailers have the following information on a plaque fixed to the trailer:
1. Empty Weight – The weight of the trailer without any cargo or fluids; also called Dry Weight or Unloaded Weight

2. GVWR – The maximum weight a trailer is rated to weigh, including cargo, fluids, etc.
3. Load Capacity – The total weight of the cargo a trailer is rated to carry
on a plaque somewhere in the vehicle. This plaque also will indicate the tire size and what Pressure to which it should be inflated. This is a known amount--sample vehicles are weighed as they leave the production line. Engineers have calculated the Load Capacity (many are very low; only a few hundred pounds--after you add water, (Black water, Grey Water and Fresh Water)--also propane tanks. The owner is cautioned to never exceed the GVWR! The tire inflation pressure (not necessarily Max capacity,) although it may be max capacity is clearly labeled in each Recreational trailer.

Fast forward for this Magic ST trailer tire. The exact same tire is used in your boat trailer. The trailer and tire manufactures know that the average boater:
1. Never weighs the trailer, boat and gear put aboard.
2. Never gave a thought to the capacity of the trailer.
3. The dealer is going to include the cheapest, barely acceptable GVRW trailer . I have seen it in several new boats I have purchased, other than C Dory--and in the used C Dory's I have owned.
4. Often this is compounded by boat builders giving very optimistic boat weights, and weights which the average boater may find when trailering.

So the people who give advice are going to CYA. Give the answer which will give the least problems. That is to inflate the tire to its's max capacity. This is fine, and certainly easier than weight of the boat and gear aboard.

Now Colby I believe has the same trailer from Load Rite that I had. Surprise! It has one of those capacity tags on the frame. Mine says use 225 x 75 x 15 tires load range D. Inflate to 65 PSI (which in fact is the max cold inflation pressure.).

Some of us are cautious--and upgrade our trailer to Endurance Load Range E--same size tire. That tire has a max rating of 80 PSI--25 PSI over the 65PSI which is given on the trailer frame! So, if Colby is cautions and upgrades his trailer tires to Load Range E-and has the tire which is capable of running at 80 PSI, go against the trailer manufacture's capacity plate, and inflate the "Bouncing Ball Betty" boat trailer up to 80 PSI? The 65 PSI rates the tire to carry 2540# (single trailer on each axle.), where the 80 PSI is going to allow carrying 2830#. ( that much weight might overload the axle and trailer frame)

Bear in mind that this is exactly the same tire, which an RV manufacture to put a specific number and inflation pressure (which often is different than the max capacity of the trailer tire.)

On the Float On Trailer I had for the Tom Cat, we used 16" wheels, and the trailer was rated for a little over 13,000 lbs. The real weight was about 10,200 loaded and ready to go, so we used the inflation for that specific weight.

Yes it is far easier and it probably reduces the tire builder and trailer builder's liability by saying it is OK to go Max pressure. If you don't want to weight the trailer with boat and gear aboard that is fine.

Colby apparently felt I didn't know the difference between LT, P and ST tires. I have been towing boat trailers for over 70 years. I have owned RV's continuously for over 60 years(VW Campers to 45' Diesel Powered max size Motor home), I first drove heavy trucks (and lite trucks over) 70 years ago--and my summer job in high school and college was driving trucks which had a payload from 20,000 lbs to 50,000 lbs (Class 8) in the Calif. mountains on gravel and dirt roads and included river fords. We checked the tires on all of these vehicles at least daily when in use--including checking pressures. After difficult runs, we rechecked the tires in mid day.

Do what is comfortable for you--and be safe!
 
If you change to a different tire (even a higher capacity one) aren't you now operating the trailer outside of its design specification (i.e. what's on the data plate)? Does the data plate say if you are using D tires inflate to X psi and if using E tires inflate to Y psi? Otherwise, you are just guessing.
 
Bob, I wasn’t trying to insult your intelligence, and I apologize if you took it that way. I think both you and I are pretty wise about trailers, tires and brakes. And tact isn’t exactly my forte. I didn’t mean you didn’t know the difference between ST, P and LT. But you started discussing RV’s and trucks, and I’m pretty sure you’re not running ST’s on those. (I take RV's to mean motorized, such as a Motorhome, but I guess it includes campers too, so already some confusion on my part when discussing RV's.) I would never recommend running max psi in a LT or P tire. And I know the tire manufacturers don’t. The fact is most of the tire manufacturers and trailer shops do recommend running ST’s at their max rated pressure. I’m pretty sure the reasons for that have been stated clearly in this thread. Colby
 
Yikes ! How such a relatively simple topic has generated such a massive response. Some people type so much, must be like controling a verbal conversation. It is a ST tire on a boat trailer, inflate it to setting specified on side of tire. Enough said !
 
Thinking more about psi in our trailer tires, these thoughts/questions come to mind. And actually, as I think about them, I'm beginning to wonder if it's worth while to upgrade to LR E tires given they are still under rated to support the load of both axles on one side if a tire fails. Just doesn't seem to make since to upgrade for that reason, if running them at a lower PSI than max.

(Oh, and I did look up what's considered overinflation. Looks like 20 psi above what's needed for the load carried.)

How do the following affect the weight on each wheel?

Wind affect? I've frequently towed in cross winds of 10-15 mph+.
I know the wheel temperatures run a little warmer on the down wind side.

What about cornering?

Centering of the boat on the trailer?

Weight distribution in the boat. (Does it float level?)

Especially on dual axle trailers, when turning in a tight parking lot that places extra stress on the sidewalls, what roll does tire inflation play?

How much more firmness is provided in a higher load range tire due to more belts (ply), and how does this relate in roughness of ride? (I.e. is it the higher psi, or the addition of plys.)

Is there any reason really to upgrade load categories to provide more buffer on a dual axle trailer in case one tire blows? And if so, will running lower psi in the higher load category tire reduce from it's capibility to support that load short term? Colby

Late addition:

Yikes ! How such a relatively simple topic has generated such a massive response. Some people type so much, must be like controling a verbal conversation. It is a ST tire on a boat trailer, inflate it to setting specified on side of tire. Enough said
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I was typing all this while you posted. lol. That's the nice thing about reading. Everyone can talk without controlling a verbal conversation. You can read at your leisure, or just turn the page... But I do agree with your last sentence. (However, it looks like this same topic has generated a lot of discussion on other forums as well. :shock: )
 
san juanderer":1qsfwqds said:
Yikes ! How such a relatively simple topic has generated such a massive response. Some people type so much, must be like controling a verbal conversation. It is a ST tire on a boat trailer, inflate it to setting specified on side of tire. Enough said !
Click to expand...

You think that's a lot of conversation over PSI in a tire, join a winter biking forum and ask how many PSI you should run in you snow tire. You will have 4 time that many in the first hour alone. :lol:
 
I was pretty close to giving up on the craziness of this....I worked in the service department at a large RV dealership in Washington for a few years. The recommendation (it was 20 + years ago but doubt it really changed) is that if you upgrade tires to a higher rating, you should put 5-10 pounds more air in it than the lower rated tire you replaced and no more - regardless if it was a trailer or diesel pusher.

It might be hard to believe, but during that time I changed about 5 zillion tires on trailers or motorhomes.....We sold Monaco, Montana, Jayco, Winnebago, and few others at the time. You'd be surprised how close trailers are to the max GVW before ANYTHING is added. And the tires are......the smallest, cheapest, and lightest duty ones they could get away with.

So.....I do not blame E-trailer or any of the experts connected at the hip of risk management saying fill it on up because that tire probably doesn't have a prayer even at max PSI with how people overload the rigs. With that said, on the other side, I have seen more than 1 premium coach (with well meaning owners) roll in with washer and drier or cabinet carriage bolts ripped out of the wall/floor because of the jarring of having high load range tires filled all the way up to 125 or whatever psi because it says to fill it up to that on the side of the tire. And somebody did it because they thought they were doing the right thing. Most of the time though, I will concede, the only obvious repercussion was leaky shocks, broken springs, broken brackets, empty cabinets, and a pissed off family with a wrecked vacation.

Commercial tires on the other hand....the have a minimum rating because they realize there is such a thing.....And it's just as important as the max.

So, like I said before, do what you want and even after all this dialog I still agree with Bob. It's your money and your trailer. Use your brain and do what you think is best - it probably is :-)
 
The knee jerk max pressure instruction likely is from the legal side of the tire manufacturers business'. They see liability from overloaded trailers, low tires, high speeds, neglect and stupidity. In the case of sellers and installers, uneducated habits and the near impossibility of knowing what the customer will haul drive max pressure advice too.

The engineers don't work up tire pressure charts just for kicks. (Read this again.)
My vehicle's tires are inflated to the pressures on the door jam, not the max tire pressure on the sidewall.

Over inflated trailers damage the loads and trailers themselves due to road shock. As pointed out above, RVs too.
 
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