Tire pressure

[Nick1234]

Is it normal for tire pressure to increase 10-12 psi while traveling? I put 65psi cold pressure in my tires and I have a tpms monitoring system. During my daily travels, the tires reach 75-76 psi. Makes me somewhat nervous.

[MtnTrek]

That's normal, raise your high alarm pressure. Resist letting any air out, the tire engineers have allowed for the operating pressure increases.
Use the recommended cold (ambient) pressure. Air your tires in the morning / evening out of direct sunshine.
Be well.

[jadatis]

If you are driving at outside temp of 65 degr F , and about 55m/h , this 10/12psi rise for a 65 psi tire is a bit much, and means that you should use a higher presssure to prefent your tires from overheating.

But it can also be that you filled at 65 degr F thaht 65 psi, and you are driving at an outside temp of 90 degr F , and then the inside tire temp is also higher, wich rises the pressure more.
Together with a higher speed then 55 m/h . it can give that pressure rising.

Normal is when outside 65 degr F, that when driving about 55m/h, the inside tire temp rises to 110/115 degr F, and by that the pressure rises by 10 to 11%,
This is for your 65psi at 65 degr F filled, say 7 psi rise.
So its not the high pressure that is bad, but the high temp of the hottest part of rubber, wich is probably in line with the inside tire-temp.

So to give your tires a lower inside tire temp, you have to give it lesser deflection, by using a higher cold pressure .
For instance if you use 70 psi, if that is what is needed for the load, then the inside tire will reach mayby only that 110/115 degr F, and the pressure will rise that 10/11% wich makes it 78 psi , wich is higher then you read now, but better for the temps

Only as example, your tires are probably not allowed more then 65 psi by the tiremaker anymore.
In earlyer days they did allow it up to 1,4 times AT for standing still , but for low speed still 1,2 times AT.
And to laws of nature , a new tire, undamaged by overheating even once, can stand a pressure of 2 to 3 times the AT-pressure of yours 65 psi.
That would be 130 psi to 195 psi , warm or cold.

So I would not go highering the pressure of your tires now then 65 psi, then you could yust have sooner a blowing tire, because your rubberstructure of tire can already be damaged.

But once you need new tires, try to find them with higher maximum load , so you can give them high enaug pressure, and stay below AT.
Then everybody happy, you because you have maximum savety margin, ,and the tiremaker, because you dont use higher then AT-pressure (cold).

[jacknife]

That is why you check a tire cold. The friction of the road heat the tire hence an increase in air pressure

[Old-Biscuit]

Hey Nick

Is 65 psi the MAX PSI (COLD) on sidewall of the 5vr tires?

YES.........
Fill to 65 psi COLD (before being driven on/before sunshine affects tire temp)
Then go camping.

Adjust (add/remove) next travel day....COLD 65 psi
Leave alone while in transit......

[rarebear.nm]

For tires in good shape with tandem axles a good rule of thumb is to cold inflate to the max. sidewall pressure rating. This is not true for single axles or Class A,B,C RVs. Do not try to adjust while driving, the tire is engineered to allow for normal pressure/temperature increases. Typically 20% above cold inflation is my max increase before I start to care. I have never seen this much increase in pressure. Tires on tandem axles have a high level of sidewall activity and its the sidewall action that creates most the heat. Higher temps create higher pressures.

the load of your RV and you're not overloading the tires. You stated your speed, which should be fine, just a point many/most tires for tandem axle 5th wheelers are rated up to 65 mph. If you drive faster then expect problems. I have seen plenty of 5ths passing me doing 70-75+ only to have tire failures a short ways on down the road. I pass them doing my standard 60-65mph.

[wingnut60]

"Do not try to adjust while driving, the tire is engineered to allow for normal pressure/temperature increases. "

True statement--every tire will have increased pressure and temperature due to friction with the road surface. Check and fill all tires at ambient temps and set the TMS at a level that accounts for this normal rise in pressure.
The MOST important situation, IMO, is to monitor all the tire pressures and watch for an anomaly--that is, one tire way different than the others. Also, IMO, tires don't fail from too much pressure, but too low pressure that allows excessive flexing, which causes more heat, which will add to probability of failure.
Don't agonize over normal pressure rise.....

[FastEagle]

Wheel & tire manufacturers account for the thermal dynamic increases and decreases and all are factored into the process of determining cold recommended tire inflation pressures.

People that often monitor their tire temps become aware what is normal and what is above the red line, so to speak. If you want to read-up on the subject, just type thermal equilibrium, (tires) in your computers search engine.

[egwilly]

My tires require 80 psi per the label. When towing, I'll see that rise to 85-87 psi depending on the road temp.
I don't worry about it. Thermal dynamics at work!