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Setting tire pressure before hitting the road

smokeylew
Explorer
Explorer
Getting ready to hit the road and want to set tire pressure on truck and trailer. Max load pressure on 5th wheel is 110 lb. I set tire pressure cold but should it be set first thing in morning or later when the day is warmer? Live in So Cal and day highs are in the 90's.

Measuring tire pressure in morning can be four or five degrees lower than measuring same tire in the afternoon. How would you set the pressure?
30 REPLIES 30

Optimistic_Para
Explorer
Explorer
If you go back and look at my first post in this thread, you'll see that I said it was FINE to inflate trailers to maximum cold pressure. It's inflating tires on tow vehicles to maximum that I warned against.

Trailers are different from tow vehicles because the dynamics are different.

"There are differences in the driving requirements between the tires on
your trailer and those on the car or light truck you use to tow it.
Therefore, there are distinct differences between the way trailer tires
and tow vehicle tires are engineered.

Your tow vehicle is a leader, which means traction is a key focus in the
design of its tires. Traction allows your tow vehicle to accelerate down
the road, turn around the corner and brake to a stop. Another important
consideration is tow vehicle tires are designed for ride comfort, which
is achieved in part by allowing their sidewalls to flex.

Your trailer is a follower, which often makes tire sidewall flexing a
negative. Sidewall flexing on trailers, especially those with a high
center of gravity (enclosed/travel trailers) or that carry heavy loads,
is a primary cause of trailer sway. Typical passenger radial tires with
flexible sidewalls can accentuate trailer sway problems. The stiffer
sidewalls and higher operating pressures common with Special Trailer
(ST) designated tires help reduce trailer sway."


That's from another Tire Rack Tech Bulletin:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=219

Atlee
Explorer
Explorer
I always inflate my trailer tires to the 65# PSI. My 6500# GVWR trailer is usually loaded to withing 500# of GVWR. Should I weight the trailer everytime I leave home, and adjust tire pressure accordingly? Should I adjust the tire pressure depending on how much on board water I've used?

And at max tire pressure, I have an even patch of tire contact on the road, as evidenced by even, from tire shoulder to shoulder, dust coverage when going to camp sites.

My truck I air up to 55# in front and 60# in the rear according to the yellow sticker inside the door jam. It has ridden fine since I got the truck. It came with OEM LT tires with E load range.
Erroll, Mary
2021 Coachmen Freedom Express 20SE
2014 F150 Supercab 4x4 w/ 8' box, Ecoboost & HD Pkg
Equal-i-zer Hitch

fj12ryder
Explorer II
Explorer II
C'mon now, don't try to counter opinions with facts, it just doesn't work.

"I've been doing this for years and it works for me, so it must be right for everyone."
Howard and Peggy

"Don't Panic"

Optimistic_Para
Explorer
Explorer
stickdog wrote:
Found it funny that a guy thinking about getting a TC is qualified to give opinions on proper tire inflation. Tell me if I'm wrong.


Would you find it funny that a guy who sold auto parts for many years, and was trained by Firestone has opinions on the subject?

And, oh yes, I've already given links to some tire tech sites that basically say the same things Firestone taught me.

But let's not stop there. How about the fact that Goodyear, on page 5 of their Recreational Vehicle Tire Care Guide says:

"Overinflating can reduce traction, braking ability, and handling, as well as result in uneven wear and an uncomfortable ride."

Or that on page 4 of the Michelin RV Tires they say the same thing?

Optimistic_Para
Explorer
Explorer
Charles2222 wrote:
Boxing gloves please


Put the popcorn away. It's not going to happen.

Optimistic_Para
Explorer
Explorer
JimK-NY wrote:

Is it even possible to increase the pressure so much that the thread does not fully contact the road? Not on any tire I have owned within any reasonable limits of the maximum allowed pressure.

Underinflation is one of the chief causes of tire failure.


OK, question for you. Why does every tire manufacturer publish charts of tire pressure vs weight carrying ability? Why don't THEY say 'Just inflate to maximum'?

Here's what a couple of the tire places have to say about overinflation:

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=1

https://tirereviewsandmore.com/driving-on-overinflated-tires-is-it-dangerous/

Charles2222
Explorer
Explorer
Boxing gloves please

JimK-NY
Explorer II
Explorer II
Optimistic Paranoid wrote:
DougE wrote:
High Pressure - no downsides.
Low Pressure - many downsides.


Disagree. High Pressure = Overinflation = Less Tread in Contact with the Road = 1 downside.


Is it even possible to increase the pressure so much that the thread does not fully contact the road? Not on any tire I have owned within any reasonable limits of the maximum allowed pressure.

Underinflation is one of the chief causes of tire failure.

stickdog
Explorer
Explorer
Optimidtic Paranoiid. I'm just one of those dumb ass's that have been towing for the last 9 years 60,000 miles+_ north-south east-west. Driven through snow and 90+ degrees. I have onboard compressor set tires to PSI at cold pressure and roll on. Found it funny that a guy thinking about getting a TC is qualified to give opionions on proper tire inflation. Tell me if I'm wrong.
9-11 WE WILL NEVER FORGET!
FULLTIME SINCE 2010
17 DRV MS 36rssb3
17 F350 King Ranch CC DRW 4x4 6.7 4:10 B&W hitch
John
โ€œA good traveler has no fixed plans, and is not intent on arriving.โ€ Lao Tzu

Optimistic_Para
Explorer
Explorer
tenbear wrote:
Do as the truckers do, hit the tire with a hammer. If it sounds ok , it is.


In point of fact, the trucker's are listening to see if all the tires sound the same. If one sounds different, then it's time to get out the tire gauge and see what's going on with it. They do it this way because it's a LOT faster than breaking out a tire gauge and actually checking each tire. And it also is based on the belief that all their other tires are correct.

If all the tires are wrong, then all the tires will sound the same and the tire thumping doesn't tell you anything.

Of course, these days, with TPMS systems, tire thumping is going the way of the buggy whip even among truckers. Eventually, it will be a completely lost art . . .

tenbear
Explorer
Explorer
Do as the truckers do, hit the tire with a hammer. If it sounds ok , it is.
Class C, 2004/5 Four Winds Dutchman Express 28A, Chevy chassis
2010 Subaru Impreza Sedan
Camped in 45 states, 7 Provinces and 1 Territory

Optimistic_Para
Explorer
Explorer
DougE wrote:
High Pressure - no downsides.
Low Pressure - many downsides.


Disagree. High Pressure = Overinflation = Less Tread in Contact with the Road = 1 downside.

DougE
Explorer
Explorer
High Pressure - no downsides.
Low Pressure - many downsides.
Currently Between RVs

fj12ryder
Explorer II
Explorer II
Ralph Cramden wrote:
fj12ryder wrote:
^^^^^^^^^^Be careful, it looks like you're complicating the uncomplicated.


... The other 9,997,000 people with RVs seem to get by without complicating checking air pressure in a tire..
And you know this how?
Howard and Peggy

"Don't Panic"