Good Sam Club Open Roads Forum: General RVing Issues: Tire Load/Inflation Calculation
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 > Tire Load/Inflation Calculation

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Grit dog

Black Diamond, WA

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Posted: 03/29/22 12:42am Link  |  Print  |  Notify Moderator

For that trailer and those tires, run them 50psi minimum.
Max pressure is a little overkill in your situation, but it’s better to run little trailer tires like that harder than minimum necessary.
I have 2 trailers with that size tires and very similar weight. 6000lbs ish. I run 50-60 psi. Unless real bad roads, I may air down the sled trailer tires for better traction. But there’s no heat when they’re covered in snow!


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2112

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Posted: 03/29/22 04:35am Link  |  Print  |  Notify Moderator

JimK-NY wrote:

bob213 wrote:

Why would Goodyear print a table for PSI if lowering the PSI damages your tires?


Note, the table is for maximum load ratings at various pressures. Most of us have had or seen tire failures and want to run at less than the maximum allowed load.
This

I went from Chinese D's to Endurance E's on a FW that has 8400lbs on 4 tires, 2100/tire. The Load/Inflation table states the MINIMUM pressure for that load should be 50lbs. The MAXIMUM pressure for the tire is 80lbs.

I initially inflated the E's to 75 lbs and it was like riding on basketballs. I ran the D's at 65lbs so I lowered the E's to 65 lbs and they rolled like silk.


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Mike134

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Posted: 03/29/22 05:57am Link  |  Print  |  Notify Moderator

I upgraded to GD endurance and also increased one size from 205-14 to 215-14 and ran them at 60 PSI for the past 8000 miles. Turns out that is too much pressure because the center of the tread is wearing faster than the edges. I'll be going down to 55 psi this year hopefully that wears them more evenly across the entire tread. The sticker on the TT calls for the OEM tires to be at 50 psi


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CapriRacer

Somewhere in the US

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Posted: 03/29/22 06:19am Link  |  Print  |  Notify Moderator

There seems to be something everyone is missing.

There ought to be a vehicle tire placard that lists the original tire size and the specified (by the vehicle manufacturer) pressure for that size. Since 2008, that placard should be located on the driver's side front corner (if a trailer), or on the driver's door frame if a motor vehicle.

There are a lot of reasons why the vehicle manufacturer might use more than what the published load tables says is the minimum.

Oh and the load tables are a MINIMUM, not a recommendation!

And tires wearing uneven (as in the center of the tread). Tires can be designed to wear evenly at a variety of pressure/load combinations, so lowering the pressure to achieve even wear is not always a good idea. Plus pressure is a minor player when it comes to even wear. There are other factors that have a much larger affect.


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Cummins12V98

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Posted: 03/29/22 06:41am Link  |  Print  |  Notify Moderator

bob213 wrote:

Why would Goodyear print a table for PSI if lowering the PSI damages your tires? If you inflate them according the the weight they are carrying I see no problem running less than the sidewall max of 65 lbs.


I went from GY "G" to GY"H" on my last DRV as I was running at the max on the G's. I contacted GY Tech Support. They said when going up in load range use the chart and add 5psi. They also said it's best to weigh each tire. I did as they said with a few years and thousands of miles on the H's they ran cool and had perfectly even tread depth at time of trade in.

They said proper inflation will give the best ride, tire wear and stopping.

They also said if running stock tires to follow RV's recommended inflation.

YES the chart is there for a reason!

Just remember there is a lot of CYA on this topic!!! A little common sense goes a long way.


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MFL

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Posted: 03/29/22 06:52am Link  |  Print  |  Notify Moderator

Agree with Capriracer, the chart is a minimum, and on a tandem axle trailer, the minimum is chart pressure plus 10%. The placard on the driver's side corner, should show the oem tire size, and tire pressure to cover the GVWR. In most cases, on a T/A trailer, this will be full sidewall max psi.

If OP is using the same size/rating tire that came on his trailer, he should be running max sidewall pressure. ST tires need air pressure to protect from belt separation, due to side scrub, and will run cooler at max pressure. If a person has jumped in tire capacity, say from a C-rated to an E-rated, you likely have too much tire for the trailer, and will have to deal accordingly.

Jerry





rfloyd99

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Posted: 03/29/22 07:19am Link  |  Print  |  Notify Moderator

OP here. I did go up a size, 205 to 215, and from C to D in load rating.

Thanks for the responses, keep them coming!

MFL

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Posted: 03/29/22 07:46am Link  |  Print  |  Notify Moderator

rfloyd99 wrote:

OP here. I did go up a size, 205 to 215, and from C to D in load rating.

Thanks for the responses, keep them coming!


Up size and rating will make a difference. You know your trailer and tow vehicle, and how the rig handles, more than we do.

My recommendation...I'd try 60 psi, check handling, ride/bounce, if okay, I'd run that. In any case, I'd not even consider going lower than the 55 psi you've been running.

Now, about those TV tire pressures? [emoticon]

Jerry

Sandia Man

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Posted: 03/29/22 08:19am Link  |  Print  |  Notify Moderator

With 3 years of RVing on these tires it sounds like you have found your sweet spot already unless tires are experiencing uneven wear. Obviously, your tires are overkill for your rig but that is a good thing in the long run. ST tires are not exactly built like LT or P tires, they tend to run and provide better performance when aired up closer to max psi as stated on sidewall.

ST tires we have had on our TTs/5ers I would make sure they had enough weight capacity to cover rig's entire GVWR, then filled them to within 10#-15# of max psi that way sidewall flex is minimal. Under-inflated ST tires will build up a lot of heat which does weaken sidewall and can eventually lead to premature tire failure resulting in tread separation or worse, a blowout while underway.

rfloyd99

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Posted: 03/29/22 08:20am Link  |  Print  |  Notify Moderator

OP again. Regarding TV tire pressure - I have a Ram 1500 gas guzzler (5.7L). I've put 100,000 miles on it, pulling the TT maybe 25,000. When on our long trips we carry the usual stuff in the truck (chairs, tools, a pancake air compressor, charcoal grill, etc., nothing really heavy) We'll have a couple of heavier things in the truck this time, maybe an extra 125 lbs. The truck is driven empty when we're not RVing.

I've always run the pressure given on the door sticker (35 psi). I've always had very even tire wear, and gotten decent mileage out of the tires.

BTW, I don't remember the exact tongue wt. when I had it weighed, but the guy said it was within the recommended range. Also, I have had no towing issues so far, such as sway, squirrely steering, etc. I never drive over 60 mph. I have new Michelin tires of the original size, and the weighing guy with Escapee's said my whole rig was within all the guidelines.

Should I run the rear tires at a higher psi on this 2,500 mile trip?, Especially since I'll have a little more weight in the back of the truck?

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