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alainP



Joined: 07 Oct 2016
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PostPosted: Mon Jan 31, 2022 2:20 pm    Post subject: Reply with quote

Salmon Fisher,
I downloaded and printed the Load/Inflation chart and looking at it (first chart up top for ST tires) I get a bit confused.
For the ST225/75R15:assuming a total load of 7500 lbs and assuming again it would be equaly distributed on each four wheels, the chart gives me a recomended inflation of 40psi.. am I looking at this right?
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hardee



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PostPosted: Mon Jan 31, 2022 2:29 pm    Post subject: Reply with quote

jkidd wrote:
I'm running Goodyear Endurance tires with tire pressure sensors. Max psi is 65 in the summer season I inflate to 58 psi. This is because by the time I have gone 20 miles they will be up to 65 psi. Later in the trip they might reach 68 psi. It bothers me to look at the display and see them hitting 75 psi. In early spring and late fall 65 psi is ok. I know there would be a margin of error that the factory would say is ok, but just try to get anyone to give you a straight answer on what that is. So how does everyone feel about running at over the max pressure?


Jody, Thanks for that info. Good to have. (No TPM's on my trailer - But I do have them on the motorcycle.) Amazing on how the temps and pressure varies, rapidly and considerably.

Question Are not the tire inflation pressures from either the charts or the sidewall stated for cold tires?

Harvey
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Salmon Fisher



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PostPosted: Mon Jan 31, 2022 2:38 pm    Post subject: Reply with quote

Yes, you are correct, that is for 1,880 lbs per tire, so approximately 7,500 lbs total. What is the maximum inflation stamped on the sidewall for, I'm assuming, your Goodyear Endurance ST tires?

40 PSI seems low to me. I would probably go with closer to the Maximum inflation for each tire since you want the side walls to be well supported as others have commented.

Have you weighed your boat on the trailer with your typical load? If you are at 10,000 lbs then you would be running a minimum of 65 PSI.

To get a true reading of tire weight, you would have to weigh each tire with your boat loaded on the trailer. Honestly, I don't know anyone who has done that.

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alainP



Joined: 07 Oct 2016
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PostPosted: Mon Jan 31, 2022 3:08 pm    Post subject: Reply with quote

Ah! I found something interesting looking at the Carlisle Tires Trailer Tire Service Guide Line,
Under an identical chart that the one for Goodyear Endurance there was this paragraph:

" 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."

well.. that clarifies a few things for some...
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alainP



Joined: 07 Oct 2016
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PostPosted: Mon Jan 31, 2022 3:26 pm    Post subject: Reply with quote

I have not weighted the boat and trailer, never found a convenient way or time to doit. Getting the boat out and back in is a bit of an undertaking.
I think ~ 7,5 K lbs is a fair estimate with little fuel and no water?
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thataway



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PostPosted: Mon Jan 31, 2022 3:47 pm    Post subject: Reply with quote

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:

Quote:
LOAD/INFLATION INFORMATION FOR GOODYEAR® ENDURANCE SPECIAL TRAILER (ST) TIRES
TIRE LOAD LIMITS (LBS) AT VARIOUS [u]COLD INFLATION PRESSURE[/u]S (PSI) USED IN NORMAL HIGHWAY SERVICE*


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.

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colbysmith



Joined: 02 Oct 2011
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PostPosted: Mon Jan 31, 2022 5:19 pm    Post subject: Reply with quote

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
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colbysmith



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PostPosted: Mon Jan 31, 2022 5:28 pm    Post subject: Reply with quote

Quote:
" 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."

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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... Mr. Green
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T.R. Bauer



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PostPosted: Mon Jan 31, 2022 5:33 pm    Post subject: Reply with quote

colbysmith wrote:
Quote:
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.


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


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.
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thataway



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PostPosted: Mon Jan 31, 2022 5:33 pm    Post subject: Reply with quote

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.
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colbysmith



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PostPosted: Mon Jan 31, 2022 7:21 pm    Post subject: Reply with quote

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. Laughing Colby
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hardee



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PostPosted: Mon Jan 31, 2022 9:57 pm    Post subject: Reply with quote

" . . . 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
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jkidd



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PostPosted: Mon Jan 31, 2022 10:07 pm    Post subject: Reply with quote

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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Salmon Fisher



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PostPosted: Mon Jan 31, 2022 10:16 pm    Post subject: Reply with quote

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.
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colbysmith



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PostPosted: Mon Jan 31, 2022 10:29 pm    Post subject: Reply with quote

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
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