Tire pressure question

[handirifle]

Looking for answers from the pro's on this.

OK, got some new Duravis tires for the 5th wheel, and so far love them. I do have a question regarding OFFICIAL opinions on tire pressures.

Here's the story.

Before we left our area (hot...90+) I checked all 4 tires, sitting right at 80 PSI (MAX Cold rating). OK All is Good. We drove to the camp site 2.5 hrs away, up north at the coast, and camped for several days. Temps there in 50's and 60's (yea we LOVE IT). Today before leaving I checked pressures again (temp is 60 deg F) and all 4 pressures right at 70 PSI. Now I know colder temps mean lower pressures, but 10 PSI seems like a lot. The tires do NOT leak. I have had them sunk in tanks to verify. They are brand new Duravis R250's, 235/85R16's that are ALL steel plys, very heavy duty tire.

I aired the tires back to 80 PSI at the 60 deg temp (mistake?)

When I got home from the trip I tested them again (temp 100deg F) and all 4 are at 90 PSI.

SO they were 80 before taking off, 70 after 3 days in cool weather, aired back to 80 and show 90 after travel in very hot weather.

Am I doing something wrong? I got home too late to call tire shop, but will call them tomorrow to get their input as well.

 

[handirifle]

I do realize that pressures will climb when towing, especially on hot days, but would they have also dropped 10 psi from sitting in the cooler climate like that? Should i have just left them at 70 and headed out? Do NOT want to over pressure the tires either.

 

[Oldpath05]

80 psi sounds like a lot for 16" tire and does sound like a lot of variation in air pressure. If I was maxing out psi, I'd make sure I had a good tire gauge if there is such a thing.

 

[handirifle]

No 80 is standard for E rated tires, it's not the wheel diameter, it's the tire and wheel's load rating. I have several gauges and have had the tire shops match them with what they use.

 

[topbuilder]

I run Es on my truck and trailers. Summer is different than winter. I don't fill to 80 because I know they will heat up.

 

[handirifle]

I will have to see what the shop says tomorrow.

 

[om21braz]

Not that I use nitrogen, but here's some data/tips and tire information:

Nitrogen in Tires : Information about Nitrogen Tire Inflation News, Benefits, Generator Dealers, Location Finder & More

 

[gary49]

If your campsite is higher in altitude than home, that might make more difference than the temperature. Right thing to do is 80 psi at home and leave them alone unless one is lower than the others at the campsite.

 

[CCWKen]

It would take a significant change in elevation to change tire pressure. On average, less than 3psi per MILE!

 

[Labrat]

I run nitrogen on my 5th wheel and my truck and see little change while towing on the truck TPMS readouts. Being an HVAC guy I always have it on hand but I now see the regulators are fairly inexpensive and a B bottle of nitrogen is less than $30.00 so it may be affordable to keep it around the house.

I'm considering a wireless TPMS for the camper. The 6 channel one will monitor the camper plus the truck and camper spare tires.

I see guys on the highway with these lifted trucks with huge tires on them towing a camper at such an angle that it puts most of the camper weight on the rear axle. I often wonder how much hotter the rear axle tires are compared to the front.

 

[Midniteoyl]

I run Es on my truck and trailers. Summer is different than winter. I don't fill to 80 because I know they will heat up.

You dont wanna do that.. They will get hotter with the lower temps. You want to minimize the sidewall flexing (which is the major cause of heat) as much as possible while still having a good contact patch. If you lower the pressure thinking they 'will heat up anyways', you are increasing the sidewall flex and thus heating them up even more than if you had aired them up. Tires can take over pressure and the OEMs make allowances for it. They cannot take excessive heat.

 

[bigtiller]

Midnite is correct. The only thing i would add is to fill the E rated tires to 80psi cold regardless the current/expected ambient air temperature.

 

[buickanddeere]

Looking for answers from the pro's on this.

OK, got some new Duravis tires for the 5th wheel, and so far love them. I do have a question regarding OFFICIAL opinions on tire pressures.

Here's the story.

Before we left our area (hot...90+) I checked all 4 tires, sitting right at 80 PSI (MAX Cold rating). OK All is Good. We drove to the camp site 2.5 hrs away, up north at the coast, and camped for several days. Temps there in 50's and 60's (yea we LOVE IT). Today before leaving I checked pressures again (temp is 60 deg F) and all 4 pressures right at 70 PSI. Now I know colder temps mean lower pressures, but 10 PSI seems like a lot. The tires do NOT leak. I have had them sunk in tanks to verify. They are brand new Duravis R250's, 235/85R16's that are ALL steel plys, very heavy duty tire.

I aired the tires back to 80 PSI at the 60 deg temp (mistake?)

When I got home from the trip I tested them again (temp 100deg F) and all 4 are at 90 PSI.

SO they were 80 before taking off, 70 after 3 days in cool weather, aired back to 80 and show 90 after travel in very hot weather.

Am I doing something wrong? I got home too late to call tire shop, but will call them tomorrow to get their input as well.

Normal, that is why the sidewall is stamped with psi cold . There are other higher priority items in this world to worry about.
They taught all about the universal gas law in high school .

 

[buickanddeere]

Nitrogen doesn't make a lick of difference . It's all about the moisture the tire's air contains .

 

[vsteel]

Midnite is correct. The only thing i would add is to fill the E rated tires to 80psi cold regardless the current/expected ambient air temperature.

+1
Check when cold and fill to 80, they are designed that they will heat up and have higher pressure.

 

[Gunny]

Midnite is correct. The only thing i would add is to fill the E rated tires to 80psi cold regardless the current/expected ambient air temperature.

What he said.

I always check my 5th wheel tires cold, never worry about them other than a visual check at every fuel stop.

 

[downsizingnow48]

On longer trips with a trailer I touch each hub and tire with my finger at fuel stops. You can feel if something is heating up compared to the others. Takes less than a minute.

 

[jajiu]

Should see if Tom Brady has a theory on this I'm sure he knows all about "inflate" "deflate" and ambient temps.

 

[bdog]

80 psi cold. Don't even bother checking them when hot from driving. I check my tires before I tow and set them to 80 regardless if it is 20 degrees or 100 degrees outside.

 

[silvertramp]

Should see if Tom Brady has a theory on this I'm sure he knows all about "inflate" "deflate" and ambient temps.

SPOT ON!!