[Wanderman]

Hey all, I am on my way to Florida from NY and notices, what i though was a pretty big increase in tire PSI on the steer axle.

I have the older 11r24.5 tires inflated to newell recommended 120PSI and I am seeing 146psi when hot after a long 62mph leg (about 400miles)

Drive at 110 went up to around 120 and tag start at 100 went up to about 108. I did begin the trip in colder weather about 20 degrees F difference. I will check cold pressure tomorrow AM.

I am just concerned about safety on the steer going from 120(122) up to 146.

Thanks,

[Richard]

I see big increases. What you saw on the drive and tag would be typical for me. I don’t see quite that much on the steer.

I have a simple tire temperature test I use at every stop. Put your hand on the tire. If you can hold it on the tire, you are probably good on temp.

The pressure goes up because the temp goes up. Check your tire temps on the front when driving. The sensors on the tire stems tell you very little about the actual tire temp. They are really good at picking up a dragging brake though.

[jadatis]

I made a pressure/temperature calculator for wet and dry. 
If you would use that, you see that the pressure rising represents a higher temperature in tire. 
I did not use it now, but your pressure rising look like no extreme temperature in tire. 

Will give a list for cold filled pressure at 70 degr F, and the degrF change per 1 psi change. 
Then you can calculate by head, while dtiving even, the new temperatures in tire. 
Pretty normal for average driving is 120 degr F of gascompund in tire. 

But if you want to play with my calculator, mail me at hotmail. com adress with username jadatis. 
Combine yourselfes, spamm-machines cant this way. 

Cold psi 70degrF/ degr F/psi
37 psi/ 10 F/psi
39 psi/ 10 F/ps
40 psi/ 9,5 F/psi
42 psi/ 9,5 F/psi
43 psi/ 9 F/psi
45 psi/ 9 F/psi
46 psi/ 8,5 F/psi
49 psi/ 8,5 F/psi
50 psi/ 8 F/psi
53 psi/ 8 F/psi
54 psi/ 7,5 F/psi
58 psi/ 7,5 F/psi
59 psi/ 7 F/psi
63 psi/ 7 F/psi
64 psi/ 6,5 F/psi
70 psi/ 6,5 F/psi
71 psi/ 6 F/psi
77 psi/ 6 F/psi
78 psi/ 5,5 F/psi
86 psi/ 5,5 F/psi
87 psi/ 5 F/psi
96 psi/ 5 F/psi
97 psi/ 4,5 F/psi
109 psi/ 4,5 F/psi
110 psi/ 4 F/psi
126 psi/ 4 F/psi
127 psi/ 3,5 F/psi
148 psi/ 3,5 F/psi
149 psi/ 3 F/psi
177 psi/ 3 F/psi

[jadatis]

Putted your pressures in my made calculator. 
Assumed cold pressures at 50 degr F measured. 

Then 122 psi going to 146 psi gives/ 139 degr F dry and 131 degr F wet( so enaugh water in tire coming in by humidity. 

110 psi going to 120 psi / 90 degr F
100 psi going to 108psi / 85 degr F.
Rounded it all a bit, howmuch humidity in tire makes a little difference

And because all tires drove in same conditions and same speed, this can mean 2 things. 
Front some hanging barings or brakes. 
Or the uses tirepressures are out of balance, and front needs higher cold pressure, wich most think is not allowed, but 10 psi extra is given on Continental groop tires in Europe, the 120 psi is not the maximum allowed cold pressure, but the reference-pressure. For reference-pressure and - speed the tiremakers calculate the maxload of tire.

Personscartires only give max allowed cold pressire on sidewall of between 44 psi and 51 psi and an ocacional XL 60 psi. The reference-pressure though is standard load 36 psi (EUR) or 35 psi (US) and XL 42 psi (EUR) or 41 psi (US).

But better would be, to put tag suspensionpressure lower, so more weight shifts to drive axle, and less on front and tag.  Then the needed tirepressures should be reviewed.  But reviewing is needed anyway because if the temoerature in tire differences.

If you find some writing errors, its because I all write it on mobile phone, wich askes much of fine motorics. 

.

[Guy]

I see big increases. What you saw on the drive and tag would be typical for me. I don’t see quite that much on the steer.

I have a simple tire temperature test I use at every stop. Put your hand on the tire. If you can hold it on the tire, you are probably good on temp.

The pressure goes up because the temp goes up. Check your tire temps on the front when driving. The sensors on the tire stems tell you very little about the actual tire temp. They are really good at picking up a dragging brake though.

Could steer tire temps be raised by alignment ( toe ) settings ? Driving in crosswinds ?