Tire pressure

[Opa 1]

I am changing out my trailer king trailer tires on new Sprinter 30RL to Goodyear Endurance. The are 10 ply with a pressure rating max 80psi. The 5er is probably 11000lbs plus or minus loaded. My friend says run 78 psi and the tire store recommended as los as 50 psi and as high as 70 psi, but recommended 60 or 65 psi

What tire pressure do y’all recommend?

[flybouy]

Run the pressure indicated on the tire placard located on outside of the trailer toward the front on the driver's side. That's a minimum cold inflation, for a maximum look at the tire pressure max rating on the sidewall of the tire.

[GHen]

X2 run the pressure on the tires. 78 is close enough, but that’s my opinion, others may disagree.

FYI, inflate when tires are cold. If you fill on a 70 degree day and you check them in the morning at 35 degrees and they are all a few degrees less, don’t worry. Also once you start driving they could get in the mid 90s, don’t let air out. They are designed for that.

[JRTJH]

AIR PRESSURE (not tire ply rating) determines the load carrying capacity of any tire. ST tires are designed to operate at maximum rated pressure. We buy and operate ST tires, not for tread wearout but rather for a specified time period (usually 5 years)...

To buy LRE tires and operate them at 50 PSI forces those tires to only be able to carry the same as a LRC tire. To operate them at 65 PSI forces them to only be able to carry the same load as a LRD tire.

So, reducing tire pressure (often thought as softening the ride) in reality, only reduces the load capacity of the more expensive tire, making it perform like the cheaper version...

Why anyone would install LRE tires, then "air them down" so they perform like LRC or LRD tires is, IMO, the same as adding extra alcohol to a gallon of gas so it fills the tank faster (but may ruin the engine with reduced performance)....

Run the tires at the "trailer placard recommended pressure" which, on all the Keystone trailers I've seen, is the same as the tire sidewall "maximum pressure"... If upgrading to a heavier load range rating, I'd recommend increasing air pressure to take advantage of why you bought "heavier tires" which, for most of us, is to get more safety margin... Reducing air pressure reduces that safety margin and defeats the purpose......

[Opa 1]

Thank you, when I get the tires home from the tire store today (still waiting on my F350). I will check the rating on the trailer and add air accordingly.

This site is really nice any questions I have had to date have been answered politely and given me a path forward that I was looking for

Thank y’all

[CWtheMan]

Originally Posted by Opa 1

I am changing out my trailer king trailer tires on new Sprinter 30RL to Goodyear Endurance. The are 10 ply with a pressure rating max 80psi. The 5er is probably 11000lbs plus or minus loaded. My friend says run 78 psi and the tire store recommended as los as 50 psi and as high as 70 psi, but recommended 60 or 65 psi

What tire pressure do y’all recommend?

It looks like you're just changing name brands, with the same designated size (ST225/75R15 LRE). Therefore, the correct inflation pressure for the Endurance tires will be the same as for your OE tires. That is most likely 80 PSI and will be depicted on the vehicle certification label, tire load and inflation placard and in the vehicle owners manual.

[Lindyn]

The tires will have a cold pressure number, however when on the road at highway speeds, tire press will increase 10+ percent, which is normal.

Happy trails.

[Opa 1]

Got home put the tires on checked the placard on the trailer and as y’all said 80psi. Next project set up the tire minder ��

[wiredgeorge]

Originally Posted by Opa 1

Got home put the tires on checked the placard on the trailer and as y’all said 80psi. Next project set up the tire minder ��

Welcome and the TPMS is a wonderful idea. You never really have much feeling for a loss of pressure when going down the road with a two axle camper until y you hear a bang as your wheel well gets blown up. When I bought my TPMS the Tire Minder system I wanted was out of stock and I bought another brand it has worked pretty darn well although a bit hard for a slow witted person like myself to set up. Fortunately the customer service folks at that company walked me through the set up process. It also makes sense to me to get one with its own monitor so you don't have to fumble looking at your phone. I have a 28' 5th wheel and don't need a repeater as some systems have them. My in-cab monitor picks up the four tire sensors nicely.

[Opa 1]

Probably good advice, but I choose the one that works with my phone. Hope it will work fine.

[jadatis]

Needed pressure is all about load on tire and maximum speed you use.

Its to give the tire a deflection that wont overgeat any part of the rubber.

Maxload of tire is calculated for referencepressure ( D- load 80 psi almost always) and referencespeed ( ST 65mph, even the Endurance with speedcode N max 87mph)

I am able to calxulate a highest pressure that wont give bumping, so highest reserve for things like.
Pressureloss in time.
Inaccurate reading of pressure( worst case scenario to high read)
But more for misyudged weight on seperate tires
Weighing is best , but fully loaded as going on trip.
Best per axle-end, but per axle can do.

The vehicle-maker uses GAWR with no reserve.

So give me
Tiresise
Maxload or loadindex
Loadrange or pressure behind AT written ( E-load AT 80 psi)
Speedcode not needed.

From TT
Number of axles and wheels
GVWR and GAWR.
Or better real weighed loads.

[travelin texans]

Originally Posted by jadatis

Needed pressure is all about load on tire and maximum speed you use.

Its to give the tire a deflection that wont overgeat any part of the rubber.

Maxload of tire is calculated for referencepressure ( D- load 80 psi almost always) and referencespeed ( ST 65mph, even the Endurance with speedcode N max 87mph)

I am able to calxulate a highest pressure that wont give bumping, so highest reserve for things like.
Pressureloss in time.
Inaccurate reading of pressure( worst case scenario to high read)
But more for misyudged weight on seperate tires
Weighing is best , but fully loaded as going on trip.
Best per axle-end, but per axle can do.

The vehicle-maker uses GAWR with no reserve.

So give me
Tiresise
Maxload or loadindex
Loadrange or pressure behind AT written ( E-load AT 80 psi)
Speedcode not needed.

From TT
Number of axles and wheels
GVWR and GAWR.
Or better real weighed loads.

Sounds like a lot of calculations!
I use what's on the sidewall, no calculator necessary.
After 40+ years I've only had 1 tire issue & that was from using a LT on a heavy 5th wheel, user error.

[jadatis]

Nothing wrong with LT on 5thwh, if maxload is with comfortable reserve to the real loads.

In Europe on travel trailers C-tires ( is same as LT only other name) are often used D-load , but sometimes even XL normal car tires ( P-tires Extraload)

As long as maxload of tires is with comfortable reserve to the axleload , they last up to 10 years.
Your LT had probably poor or no reserve.

Let me do the calculating, you only have to provide the data.

[Opa 1]

Thanks y’all. This morning I set the tires at 79psi cold set up the tire minder this afternoon the sunny side of the camper read about 81 psi the shady side was just below 80 psi.

Now I just need the truck. My dealership told me it is somewhere between Birmingham and New Orleans. So it should be here soon I guess.

[wiredgeorge]

Originally Posted by Opa 1

Thanks y’all. This morning I set the tires at 79psi cold set up the tire minder this afternoon the sunny side of the camper read about 81 psi the shady side was just below 80 psi.

Now I just need the truck. My dealership told me it is somewhere between Birmingham and New Orleans. So it should be here soon I guess.

Hey! While you are at it, put together a signature with your camper & tow vehicle year, make and model. Will help give some context to your questions. As far as tire pressure, look at your sidewall... 80 PSI for LRE tires for the most part. That is where the tires deliver the load rating they claim. We often make this too complicated.

[friz]

Originally Posted by JRTJH

AIR PRESSURE (not tire ply rating) determines the load carrying capacity of any tire. ST tires are designed to operate at maximum rated pressure. We buy and operate ST tires, not for tread wearout but rather for a specified time period (usually 5 years)...

To buy LRE tires and operate them at 50 PSI forces those tires to only be able to carry the same as a LRC tire. To operate them at 65 PSI forces them to only be able to carry the same load as a LRD tire.

So, reducing tire pressure (often thought as softening the ride) in reality, only reduces the load capacity of the more expensive tire, making it perform like the cheaper version...

Why anyone would install LRE tires, then "air them down" so they perform like LRC or LRD tires is, IMO, the same as adding extra alcohol to a gallon of gas so it fills the tank faster (but may ruin the engine with reduced performance)....

Run the tires at the "trailer placard recommended pressure" which, on all the Keystone trailers I've seen, is the same as the tire sidewall "maximum pressure"... If upgrading to a heavier load range rating, I'd recommend increasing air pressure to take advantage of why you bought "heavier tires" which, for most of us, is to get more safety margin... Reducing air pressure reduces that safety margin and defeats the purpose......

Sage advice.

[Opa 1]

Thank you, I will test my limited IT skills and try to add this signature

[Opa 1]

Wow it worked thanks again

[hazmat456]

[Opa 1]

Thanks for the nice chart. the trailer placard says 80 psi cold and the tire sidewalls say 80psi cold. The tire size is ST225 75R 15E. I do not see this size and rating on this chart but I assume they would be the same as the 16” wheel which also says a 80psi