confusion on psi on TT

[baileyandnat]

Hello! I have a new trailer and I bought a TPMS for our upcoming long trips. I got confused when i was installing my system on what my psi warning should be? The sidewalls says 65psi cold max. Is that what i should have my tires inflated to or should i not exceed 65psi? What should i put as my warning setting on my TPMS? Thanks for helping a newbie out.

 

[Bob K4TAX]

The sidewall pressure is the MAXIMUM the tires should be inflated when cold. Otherwise having not being towed and allowed to heat. Thus ambient temperature. This also assures the tires can safely carry the maximum rated load for the tire. There is no reason to inflate to less than the MAXIMUM pressure as posted on the tire. If it says 65, then inflate to 65.

Underinflated tires will heat during rolling and may be prone to early failure due to excessive sidewall flexing. Underinflated tires are dangerous.

 

[Buly]

If you fill in all your inf about the coach type, model etc. people will know what ate you talking about. But in general, the tire inflation depends on the weight applied on the tire.
You should weigh the RV under each tire fully loaded. Than the tire manufacturer usually has tables that you can look up the inflation pressure for your tire against the weight.
The number on the tire, only means max inflation limit.

 

[sanda]

If you fill in all your inf about the coach type, model etc. people will know what ate you talking about. But in general, the tire inflation depends on the weight applied on the tire.
You should weigh the RV under each tire fully loaded. Than the tire manufacturer usually has tables that you can look up the inflation pressure for your tire against the weight.
The number on the tire, only means max inflation limit.

I agree. Max tire pressure can create poor wear/life of a tire if the load is much less than the max load on the tire. Weigh the trailer fully loaded and divide by four to get a close idea of your true per tire load. Adjust pressure to the manufacture recommendations.

 

[BGMAC]

I agree. Max tire pressure can create poor wear/life of a tire if the load is much less than the max load on the tire. Weigh the trailer fully loaded and divide by four to get a close idea of your true per tire load. Adjust pressure to the manufacture recommendations.

I tend to disagree with max psi creating poor tire wear. (Radial Tires)
with the tire at max pressure the tire has less deflection when in contact with the ground. This allows for easy rotation thus less heat thus less wear. It also decreases hydroplaning.

There was an articulate about this I believe in Road & Track magazine back in the 70’s to increase your tire pressure to 15psi over the rating of the tire on radial’s. I’m not advocating that, but I have done it. There are many studies on this with aircraft tires and there are videos of these tests online.

here is a link to a formula to show you how tire pressure effects hydroplaning. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2919&context=roadschool

if I remember correctly, tires have to be tested to 2 1/2 times the rating on the sidewall. Pressures will increase when they get hot and that is accounted for.

 

[Buly]

Over inflated tires wear faster in the middle. Under inflated ones wear faster on both sides. You are right there is lest rolling resistance on over inflated tires. Trains with their steel wheels have the least rolling resistance .
But over inflated tires give you a harder ride, and under inflated wear faster an heat up more when in use.
It is all a compromise. Aircraft tires are a different ball of compromises. They are in fast motion only for under a minute at the time. Me thinks

 

[sanda]

In my case this is the manufacturers chart that I use.

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

 

[FL-JOE]

If you inflate those trailer tires at 60psi for example, and you are running 65mph on a sunny 90 degree day they will no doubt heat up. I would set the TPMS high heat warning to come on between 140 and 160 maybe. If I recall correctly most tires will fail above the 150 degree range.

As far as setting your psi parameters. On a hot day when towing a tire you have set at 60psi for example could have an increased psi of 75 to 80. This is normal so set your parameters accordingly. You don't want a warning to come on at 55psi nor do you want a warning to come on at 78.

Hope this makes sense?

 

[BGMAC]

Over inflated tires wear faster in the middle. Under inflated ones wear faster on both sides. You are right there is lest rolling resistance on over inflated tires.

This is mainly true with the old bias ply tires. With radials not so much as long as you have the correct tire for the rim width. It’s true. It will be a little harder ride. I’ve actually run 15 psi over the rating of the tire for many years and never wore the center of the tire (since I read the article). The truck tires I have today is rated at 45psi and I have 60psi in them now and have over 20,000 miles on them. Again I don’t advocate doing so.

 

[BGMAC]

In my case this is the manufacturers chart that I use.

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

Yes, good chart. It shows the minimum tire pressure per weight. To be on the safe side I would run a little more. Running to low a pressure causes stress on the sidewalls.