Oh Wow, another tire pressure question

[Gubs]

I have Sailun tires on my Montana, Sailun S637 Trailer Tire ST235/85R16G ... They state max PSI 110. I start with about 105 to 107 but sometimes while traveling they get as high as 120 or more, is this normal? We live in Arizona so it get a bit warm. I check my tires every time prior to leaving on a trip and every morning prior to leaving if we change camp sites, so no need to go there or cover that ground. Pretty careful about my tires, hate setting along side the interstate while traffic blows by a 90MPH. Also. tearing up the rig is not much fun either!!!

[beeje]

That is perfectly normal. Mine go from 110 to 130+ on occasion.

[scottz]

Inflate them to 110 when cold. Does not matter what you get when they are hot; they are designed to take it.

[RMcNeal]

Actually, the TPMS I have has a 158 degree high temp alarm by default. The big thing is, if your tires are getting that hot, especially quickly, you have other problems to be concerned about. Pressure can increase by 20 to 25 psi under normal conditions as the tire and road heat up while driving.

[scottz]

Originally Posted by RMcNeal

Actually, the TPMS I have has a 158 degree high temp alarm by default. The big thing is, if your tires are getting that hot, especially quickly, you have other problems to be concerned about. Pressure can increase by 20 to 25 psi under normal conditions as the tire and road heat up while driving.

I don't think he said anything about temperature, just concerned his pressure was increasing; which is normal.

[RMcNeal]

I agree. But temperature makes the pressure rise too. I could have said it a little better.

[mhs4771]

The Cold Set Point is considered set at 70 ambient. The best thing to do is just watch the pressure and temp of all the tires. As long as all are close to one another you're fine. When one is off is when you need to look for the cause before it's too late.

[PSFORD99]

Here is some things I have found on these tires ,first 110 psi covers more weight then most of us are carrying per tire , the ones that are in question are rated for 4400 lbs @ 110 psi.

I start out here when its cold in Utah in the winter, headed for Arizona , I set mine at 95, according to Sailuns weight chart I'm well covered for my weights. Between them heating up ,and the change in air temperature I am running close to 115 by the time I reach St George in Utah. Those tires that were 95 cold when I started are up over 100 cold the next morning ,and right where I want to rum them 100-105. My point is I am finding out I don't really have to mess with them at all. And the nice thing about having a TPMS is , I know before moving if all the tires are okay.

[jadatis]

Made this list with spreadsheet I made, can make it for other cold advice pressures too, and other steps in the pressure.

I go from 65 degrF, but 70 drgrF as one wrote here gives that less difference, that its not worth the discussion who is right.
Then you see that 120 psi warm means temp of inside tire air is about 130 degr F.
I once determined that when driving about 50mph at ambiënt temp of 65 degrF, temp in tire goes to 110 to 115 degrF , so 130 is a bit more.
but mayby higher speed or hotter day.
I think temp in tire , when only courced by driving, is not allowed to go above 60 degrC( is that 140 degrF?)

But going above your 110 psi at it self is no problem, the tiremakers included that in the cold pressure they give.

Once read that teststandard is that the tire must stand a 2 to 3 times the reference-pressure ( your 110 psi) ., so dont even worry about the 10 psi here.

F. / PSI
21 / 95
30 / 97
39 / 99
47 / 101
56 / 103
65 / 105 advice-pressure
74 / 107
83 / 109
91 / 111
100 / 113
109 / 115
118 / 117
126 / 119
135 / 121
144 / 123
153 / 125
161 / 127
170 / 129
179 / 131
188 / 133
F. / PSI
Greatings fro. The Netherlands, from this " pigheaded Dutch selfdeclared tirepressure-specialist"

( ja dat is ) Peter
Nickname from an old Dutch namesong, translates as " yeah that is ( Peter)

Can write for hours about it, and even made spreadsheets to calculate the pressure for Motorhomes and Travel-trailers.

[PSFORD99]

Originally Posted by jadatis

Made this list with spreadsheet I made, can make it for other cold advice pressures too, and other steps in the pressure.

I go from 65 degrF, but 70 drgrF as one wrote here gives that less difference, that its not worth the discussion who is right.
Then you see that 120 psi warm means temp of inside tire air is about 130 degr F.
I once determined that when driving about 50mph at ambiënt temp of 65 degrF, temp in tire goes to 110 to 115 degrF , so 130 is a bit more.
but mayby higher speed or hotter day.
I think temp in tire , when only courced by driving, is not allowed to go above 60 degrC( is that 140 degrF?)

But going above your 110 psi at it self is no problem, the tiremakers included that in the cold pressure they give.

Once read that teststandard is that the tire must stand a 2 to 3 times the reference-pressure ( your 110 psi) ., so dont even worry about the 10 psi here.

F. / PSI
21 / 95
30 / 97
39 / 99
47 / 101
56 / 103
65 / 105 advice-pressure
74 / 107
83 / 109
91 / 111
100 / 113
109 / 115
118 / 117
126 / 119
135 / 121
144 / 123
153 / 125
161 / 127
170 / 129
179 / 131
188 / 133
F. / PSI
Greatings fro. The Netherlands, from this " pigheaded Dutch selfdeclared tirepressure-specialist"

( ja dat is ) Peter
Nickname from an old Dutch namesong, translates as " yeah that is ( Peter)

Can write for hours about it, and even made spreadsheets to calculate the pressure for Motorhomes and Travel-trailers.

There has never been a worry about how far over 110 my tires get when heated up, unless one gets too far out of range with the others , but so far running the TPMS . I see things staying as they should . As expected the sunny side while traveling will run warmer then the shady side .

[jadatis]

Reading back, I stumbled on the ST 235/85R16 LRG with 4400lbs maxload.
That 4400 is calculated for 65mph, and that means more deflection allowed, wich gives more heatproduction, so in the end warmer inside tire air ( or whatever gascompound ).
A LT tire is calculated in maxload for 99mph, ( some 93) and my 115 degr F I based on LT advice pressure, with reserve of 10% to the real load on tire.

So the ST will get hotter at 50mph at 65 degrF.

But when I calculate pressure for ST, I first degrade maxload by 6 Loadindex-steps, to give them a deflection needed for 99mph. Together with adding reserve of 10 to the determined axleload, maximum reserve with still acceptable comfort and gripp, for TT no bumping.

Found out that system, the tiremakers also use.
Rule of tumb is for every 10kmph/6.5mph different used speed, 1 Loadindex step different.
Higher speed》 lower loadindex.
Lower speed》higher loadindex.
Its all done for the temp of tire rubber, not to go above a critical temp, where it hardens, and beginning cracks are made. Then tge tire in fact is lost, but can take even 3 years before damage builds up that farr that tire blows, or treath seperates, with all the missery that can go with it.
Then that once going over the limits, is long forgotten, and tirebrand or origen ( China Bombs) is blamed.

[jadatis]

Answer to post #10.
From topicstarters opening post, I judged that he was a bit worried about going over 110 psi, but mayby I misunderstood.

Anyway, I think my shared nolledge, will make it clearer for him ( or mayby even more confusion).

[jadatis]

Originally Posted by PSFORD99

Here is some things I have found on these tires ,first 110 psi covers more weight then most of us are carrying per tire , the ones that are in question are rated for 4400 lbs @ 110 psi.

I start out here when its cold in Utah in the winter, headed for Arizona , I set mine at 95, according to Sailuns weight chart I'm well covered for my weights. Between them heating up ,and the change in air temperature I am running close to 115 by the time I reach St George in Utah. Those tires that were 95 cold when I started are up over 100 cold the next morning ,and right where I want to rum them 100-105. My point is I am finding out I don't really have to mess with them at all. And the nice thing about having a TPMS is , I know before moving if all the tires are okay.

And that is also my conclusion, once set a pressure, checking is OK, but dont mess with it further.
Cold advice pressure is determined for 65degrF ( or 70 ..whatever) when for instance 40 degrF 》 lower pressure》 more deflection》 more heatproduction at same speed. But also more temp-differences between rubber and in and outside tire air, so better cooling down, so rubber still wont reach its critical temp.
Highening up to determined advice is not needed, but is allowed for road-handling.

But now 95 degr F outside.
Higher cold pressure needed, gives lesser deflection so lesser heatproduction at same speed. But then lesser temp-differences between rubber and in- and out-side tire air, so lesser cooling down.
SO THEN NEVER LOWER THE PRESSURE TO DETERMINED ADVICE.

Within a certain range of outside temperature, cooling dow and heating up of rubber of tire stays in balance, so rubber dont reach its critical temperature.

[Cyride]

I talked with my tire manufacture and they told me to inflate the tire pressure to the recommended pressure label on my 5th wheel (which also matches the pressure on the tires) at the ambient temperature right before I leave. Before that I would set the pressure slightly low in the morning to allow for daytime warning. The manufacture said, in writing through email, the tires are designed to handle tire pressure increase as ambient temperature increases. The manufacture said the worse thing I could do is to under inflate the tires as that will cause excessive heat and ware. I have my TPMS alarms set to monitor temperature and pressure according to the manufactures recommendation also. I would imagine if I started out in the morning and ambient was 40F and in the afternoon the temperature was very hot, if I started to get alarming on my TPMS I would stop, allow the tires to cool down and inflate the tire pressure at the current ambient temperature. Haven't had to do that yet. I carry a compressor on board and check my presser just before I get on the road every day.

[Ram Montana High Country]

You've gotten good advice - my TPMS gives me great comfort. What I really look for is constant similarity between the four tires. A bearing problem or brake problem could spike an individual tire temp, stop real soon and find out why. You might find one side runs hotter or one tire might be different. As long as it's consistent, you are good to go.

[Cyride]

It's interesting watching the TPMS while traveling. The side of the 5th wheel that has the sun shining on it will have a higher temperature/pressures. Also, when the wind is hitting the side of the 5th wheel the opposite side will run warmer and a little higher pressure. My Montana HC has 6 wheels, I would not be without TPMS on either the truck or RV. Those low pressure alarms come in right away when I test them. It gives me a lot of comfort knowing what is happening back there! When I bought the RV and we were close to making the deal I told them to throw in the rear camera and TPMS and they did. I would have put them on even if they had told me no.

[richfaa]

at the seminars at the fall rally it is recommended that we inflate the tire to the pressure indicated in on the tire which we have always done. We have the TPMS so we are aware of our Tire pressures on the truck and RV at all times. We have been alerted to a loss of pressure a couple of times over the years and stopped before any damage.