Proper Tire Presure

[Beerdawg]

What should the proper tire pressure be on ST205/75R15 tires on a travel trailer? Thanks

[Oldme]

AH64ID wrote:
I have yet to see a trailer with recommended pressure on a sticker, but every trailer tells you max pressure at max load.

Tire manufacturers publish load/inflation charts for a reason, proper pressure is the pressure at which the tire can support the load applied.

Overinflated isn't as bad as underinflated but still has drawbacks such as decreased traction, decreased tread life, increased susceptibility to road hazards, and transfer more road imperfections to the trailer.

The correct answer to weigh your axles and adjust accordingly. 5 psi over chart pressure is also recommended, up to sidewall max, if you will be driving 60-65 for a long ways. Until you can weigh your trailer run max pressure, but do weigh it.

X2

[JIMNLIN]

Beerdawg wrote:
What should the proper tire pressure be on ST205/75R15 tires on a travel trailer? Thanks

I'll repost the OP question.
If the OP tires are Carlisle trailer tires he will have to use max sidewall pressure per Carlisle tire warranty. Other ST tires brands may have that in their warranty clause also.

From Carlisle ST tire warranty pages; (snipped)

-Maintain air pressure at the maximum PSI recommended on the tire sidewall.

-The Warranty is void if the tire or wheel fails due to damage from improper inflation pressures, exceeding the maximum speed limit, or overloading the tire beyond the maximum load capacity stated on the sidewall

[Cummins12V98]

AH64ID wrote:
I have yet to see a trailer with recommended pressure on a sticker, but every trailer tells you max pressure at max load.

Tire manufacturers publish load/inflation charts for a reason, proper pressure is the pressure at which the tire can support the load applied.

Overinflated isn't as bad as underinflated but still has drawbacks such as decreased traction, decreased tread life, increased susceptibility to road hazards, and transfer more road imperfections to the trailer.

The correct answer to weigh your axles and adjust accordingly. 5 psi over chart pressure is also recommended, up to sidewall max, if you will be driving 60-65 for a long ways. Until you can weigh your trailer run max pressure, but do weigh it.

So far on my new 16 MobileSuites I have not seen anything about air pressure. The rig did arrive with 115psi in all 4 tires. After I weigh each wheel I may end up lowering to 110. The tires are GY "H" with a max pressure of 125psi.

But the fact is "MOST" RV's should run MAX pressure because they have these RV's maxed out based on the carrying capacity of the POS tires they install.

[DSDP_Don]

Typically, you weigh an RV and than adjust the tire pressure. This is done for ride quality so you don't get beat to death. Trailer tires are the exception. As everyone has told you, max pressure is where you should start. I would run them that way and keep an eye on them. If max pressure is too much, you'll start the see the center of the tires wear more quickly. If they do, drop 5 psi.

[AH64ID]

kellertx5er wrote:

AH64ID wrote:
I have yet to see a trailer with recommended pressure on a sticker ...

Really? EVERY trailer I have seen has a sticker with recommended tire pressure, same as any car or truck.

Post up a pic...

Every trailer I have seen has a pressure for max cold sidewall pressure for max rated axle capacity. Max capacity and actual loading are generally different and such require different pressures.

Just like on a vehicle the sticker tells you to run "x" psi if you are loaded at axle capacity.

It's nothing more than a max and should not be confused, thou generally is especially on this site, with proper pressure.

My trailer has a sticker that says 65 psi, max sidewall, for loading the 5200lb axles up. The owners manual then goes on to tell you to run max until you weigh the trailer and then adjust for your loading.

Max loading @ max pressure should be on every vehicle or trailer... recommended pressure @ actual loading will not be on the trailer because the mfgr doesn't have any idea how heavy you will load it.

[kellertx5er]

AH64ID wrote:
I have yet to see a trailer with recommended pressure on a sticker ...

Really? EVERY trailer I have seen has a sticker with recommended tire pressure, same as any car or truck.

[dave54]

Two additional points: check the spare in addition to to the on-the-ground tires. Nothing is worse is than finding out the spare is as flat as the tire on the ground. Murphy's law says you will discover the condition of the spare on the side of a high speed highway in the rain.

Second -- regardless of the speed rating on the LT tire, it is still limited to 75 mph if it is on a trailer or 5th wheel.

[Turtle_n_Peeps]

I tow fast in hot weather so for me max pressure or max +10. And no, I don't have tire problems.

[Lauren]

I went thru this dialog a few years back after 4 blowouts - no accidents, thank God, but some trailer damage. Many, many discussions on here with with tire manufacturers, etc.

Bottom line was trailer tires at max at cold / ambient temps -- BEFORE you start driving.

The pressure buildup when driving is built into the tire design.

And I check all tires - 5er and truck - frequently. And carry a good compressor.

God willing, I will not have another blowout.

[coolbreeze01]

PSI for loading might be ideal, but the load on each tire doesn't stay static going down the road. Liquid shifts position as well as centrifugal forces on curves.

Max PSI allows the tires to perform to their rated load as demands change.

[AH64ID]

ST tires and car/truck tires are different, but there ARE load/inflation tables specifically for ST tires.

Stating one Should inflate to max sidewall pressure is a technique, but it is NOT the one recommended by the tire manufacturer or most trailer companies (at least every manual I have looked at says to adjust trailer tire pressure for the load). The one recommendation that should matter is the one by the tire manufacturers.

I have lots and lots of miles with ST's at proper pressure, not max, at sustained speeds up to 70-72 and have never had a neat related failure in 20 years of dragging trailers. Some trailer where at, or slightly above, load capacity and some where well under.

The OP asked for proper pressure not how to run them overinflated as most have recommended.

http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[Campfire_Time]

LarryJM wrote:

Ranger Smith wrote:
There are at least 100 topics on this. It has to do with the weight on each axle and tire . . . Do a search

frankdamp wrote:
Do NOT use the max pressure molded into the sidewall. That's the maximum the tire can take without blowing up (with a safety factor, of course). You need to weigh the load on the tires (when typically loaded for a trip), then consult the tire manufacturer's load/pressure chart.

As an example, the tires on my Kia minivan are rated to 45 psi by the molded # on the sidewall. The vehicle manufacturer recommends 34 in the front and 38 in the back. With our typical load (me, DW and our two Labradors) the weighbridge numbers suggest 31 front and 35 rear. The Toyos I have on the van are at about 55,000 miles (van has 120K) and are still in good shape, using those numbers.

Both of the above quotes are IMO WRONG for ST tires which is what was asked about. While using pressures based on load inflation for normal vehicles has merit, tires on trailers and especially ST tires should be inflated to the max pressure listed on the sidewall as almost all of the other posts in this thread so far have recommended.

Larry

X2! Thank you Larry for clarifying this. ST tires and car tires are two different animals altogether.

[Chris_Bryant]

Another vote for sidewall pressure for the reasons Larry and others have given.
I'm probably one of the few people who has worn out trailer tires @ 90,000 miles.

[LarryJM]

Ranger Smith wrote:
There are at least 100 topics on this. It has to do with the weight on each axle and tire . . . Do a search

frankdamp wrote:
Do NOT use the max pressure molded into the sidewall. That's the maximum the tire can take without blowing up (with a safety factor, of course). You need to weigh the load on the tires (when typically loaded for a trip), then consult the tire manufacturer's load/pressure chart.

As an example, the tires on my Kia minivan are rated to 45 psi by the molded # on the sidewall. The vehicle manufacturer recommends 34 in the front and 38 in the back. With our typical load (me, DW and our two Labradors) the weighbridge numbers suggest 31 front and 35 rear. The Toyos I have on the van are at about 55,000 miles (van has 120K) and are still in good shape, using those numbers.

Both of the above quotes are IMO WRONG for ST tires which is what was asked about. While using pressures based on load inflation for normal vehicles has merit, tires on trailers and especially ST tires should be inflated to the max pressure listed on the sidewall as almost all of the other posts in this thread so far have recommended.

Larry