Cold PSI raises fast when driving

Charles.maine · 06-13-2016, 07:16 AM

So I have read over and over and over that you set the cold psi to the max. I have Goodyear G614s with max PSI of 80. After about an hour or so of driving the temps are about 10-15 degrees above the outside air temp. My concern is the PSI shoots up to 105-115. Is this something to worry about?

KingFisher · 06-13-2016, 08:03 AM

I've been wondering about this also.

Tfort · 06-13-2016, 08:10 AM

The pressure should not climb that much. 5-10 psi max should be about all you should see.

2000 F250 CC 4x4 7.3L diesel

15 Salem Hemisphere Lite356QB

SeaDog · 06-13-2016, 08:15 AM

When the tire mfg sets the cold pressure they understand that the pressure will climb and the max cold pressure accounts for this. Your 20* temp climb does not seem to be normal there may be other factors involved. Speed, weight, alignment etc.

clr · 06-13-2016, 08:33 AM

This may be a question for wtire a real tire expert. But I know when I set up my tire pressure monitoring system they said to set the high pressure alarm point at 20% above the normal cold tire set pressure. So if you set your tire to 80 PSI cold that would be 96 degrees F for the high pressure alarm point. So your increase to 105-120 PSI would set off the high pressure alarm. Sorry but I do not have a fix for you here.

Jim34RL · 06-13-2016, 08:33 AM

First off do you have TPMS on the trailer tires?

If so how accurate are the sensors; IE what is the tolerance range on them?

What is your background for determining that the tire pressure is too high when the tire has heated up do to rolling resistance!

Have you weighed the trailer and the individual tire to determine the weights to see if one tire is overloaded or the trailer?

**Tireman9** · 06-13-2016, 08:36 AM

Quote:

Originally Posted by Charles.maine

So I have read over and over and over that you set the cold psi to the max. I have Goodyear G614s with max PSI of 80. After about an hour or so of driving the temps are about 10-15 degrees above the outside air temp. My concern is the PSI shoots up to 105-115. Is this something to worry about?

I agree that a temp increase of only 10 to 15F should not result in pressure increase of 30 to 45 psi. Something is wrong.

What brand TPMS?
Have you confirmed TPMS pressure against a known accurate digital hand gauge?
What are your measured tire loads?
What speeds were involved?

I only see about 8 - 10 psi with 10 to 15F at 63 mph. Of course I have at least 20% margin on load.

Davidg · 06-13-2016, 08:45 AM

Quote:

Originally Posted by Charles.maine

So I have read over and over and over that you set the cold psi to the max. I have Goodyear G614s with max PSI of 80. After about an hour or so of driving the temps are about 10-15 degrees above the outside air temp. My concern is the PSI shoots up to 105-115. Is this something to worry about?

Isnt the max pressure in the G614, 110 psi? For the size of your fiver, 80 psi may be way to low which would cause over heating which results in pressures rising disproportionately. If you start out with 110 psi, the tire will run cooler.

Charles.maine · 06-13-2016, 08:52 AM

I will double check the information when I get home and report back.

**Flybob** · 06-13-2016, 09:01 AM

Per Goodyear site.
Size
LT235/85R16 Capacity 3,750 LBS @ 110 PSI
Ply Rating 14
Service Description 126/123 L
Diameter 30.7" Width 9.5"
Tread Depth 12/32

NMWildcat · 06-13-2016, 12:33 PM

I agree with everyone... 10 -15 is the most I see and down here it's 105 during the day. And the G614 tires I'm seeing do have a 110 cold psi so under inflation could be your problem.

The only time I've seen higher pressure differentials is when I set the cold psi in the tires when I am in a 'cold' climate and then drive down to the 'hot' climate. Air expands as it heats so you have to account for that when setting cold pressures. But I'm talking about going from 65 degrees weather to 100 degrees (Ruidoso NM to Alamogordo NM).

Good luck!

**Tireman9** · 06-13-2016, 01:07 PM

Info that may be of interest to many.

I did the math in a post on my blog and confirmed we should see 1.88% change in inflation per 10°F according to Gas law.

Just completed 6 tire experiment of Saturday drive of 5 hrs Indiana to Ohio with ambient around 85 - 90. Compared with today with RV in car part in shade since Sat night. It was 50°F ambient last night and is now 60-70

I found a range of 1.93 to 3.29 % increase for 10F increase with 6 tire average giving 2.57% per 10°F.

I am contacting some other tire folks to see what actual observations they have.

HOWEVER I do not believe the difference between theoretical 1.88% and 2.57% to be meaningful difference for the purpose of providing guidance for the RV community. For a few years I have been suggesting a "Rule of thumb" of 2% per 10F.

Tonylmiller · 06-13-2016, 01:45 PM

I agree with 2% for 10 degrees F. Problem lies in measuring the temperature inside the tire accurately. The tread and the wheel are not the same temperature. Just check the pressure with a good handheld gauge.

Charles.maine · 06-13-2016, 06:25 PM

I am an idiot. Complete waste of a thread. So the tires had 106-108 in all 4, cold sitting in the garage. I don't know where I got the 80 from. Max is 110 and so them running hot around 110-115 is totally normal. Thanks for all the insight.

**Tireman9** · 06-13-2016, 06:30 PM

Well that was easy. Solved that problem in less than a day.

Airdale · 06-13-2016, 07:49 PM

Quote:

Originally Posted by Charles.maine

I am an idiot. Complete waste of a thread. So the tires had 106-108 in all 4, cold sitting in the garage. I don't know where I got the 80 from. Max is 110 and so them running hot around 110-115 is totally normal. Thanks for all the insight.

Maybe your trailer was originally equipped with LRE tires and you got the 80 from the tire placard.

If you have plus sized your tires to LRG you should set a new cold tire pressure to go by and write it on a note and post it next to the tire placard.

Charles.maine · 06-13-2016, 07:54 PM

I always go off the tire sidewall. I don't know what I was thinking. Maybe the old tires who knows.....

Davidg · 06-13-2016, 10:23 PM

Quote:

Originally Posted by Charles.maine

I am an idiot. Complete waste of a thread. So the tires had 106-108 in all 4, cold sitting in the garage. I don't know where I got the 80 from. Max is 110 and so them running hot around 110-115 is totally normal. Thanks for all the insight.

Nope, not an idiot, and not a waste at all. There is probably someone who learned something as a result. And Charles, if nothing else, you made everyone else feel better, because we've all made little mistakes, and a few big ones from time to time.
I'm actually quite happy to read your post above because I've been a little worried that you had been running them with to low a pressure causing high temps, and it would be a shame to lose a fine set of tires that way.

So I'm happy for this outcome.

dieselguy · 06-13-2016, 10:29 PM

I was getting ready to chime in that any of my RVing buddies with G614's run 105 - 110 psi cold. You already made that discovery .......

MuddauberE · 08-23-2020, 07:48 PM

Quote:

Originally Posted by Davidg

Nope, not an idiot, and not a waste at all. There is probably someone who learned something as a result. And Charles, if nothing else, you made everyone else feel better, because we've all made little mistakes, and a few big ones from time to time.

I'm actually quite happy to read your post above because I've been a little worried that you had been running them with to low a pressure causing high temps, and it would be a shame to lose a fine set of tires that way.

So I'm happy for this outcome.

4 years later I found what I was looking for in this thread. Not a waist. I was about to post a similar question but after searching I found this thread and it answered it. I was trying to find out what a safe pressure rise while driving on the highway would be. This thread explained a safe level and even when set to max PSI cold. Thanks for saving me time even if you felt it was a waste. [emoji106]

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