Tire Pressures... what is correct

[PS Cruisign]

ACE you are totally forgiven if that even applies... why here. We say what we feel... i did.. you did. I just dont pull punches...

Look forward to your replies in the future... please tell me what you think..


I will do what I feel... and you will tell what you do...

just rubbed me the wrong way..

perhaps I was in error..

cheers

[phoeg]

If I might reignite this thread…

Just wanted to say it was helpful. I am only in my second year of RVing (2016 Hurricane 34F) and wondered the very things mentioned here.

I’m about to depart Albuquerque and it’s 40° outside. Sticker inside the coach says 95 psi cold. I have that on all 6 tires. I know Amarillo will see a high of about 74° today. I've decided not to worry about "chasing" tire pressure and just keep an eye on the TPMS (which, oddly, reads about 2 psi lower than my gauge, but that gives me something to bear in mind). I did that on the trip out from Oklahoma City to Santa Fe and the pressures seemed fine with changes in altitude and temps.

Thanks for the helpful info.

Paul

[simidrm]

Originally Posted by Sweetbriar

The thing is you're constantly chasing a number attempting to achieve multiple conflicting goals. You can set for a comfortable ride but your compromise mileage or you can reduce for fear over over inflating but when temperature cools you'll be under inflated or,,,,. The problem is changing pressure on a hot tire will cause other problems later, specifically where the pressure will end up once the tire and air cools down, at 3AM.

Use the TPMS to monitor (the M in the name). Easy to do a quite check in the morning and ensure the numbers all look good, above minimum. On the road you're looking for consistency. Pressures and temps are rising about the same percentage. There will be some variation and you just need to get a feel for your configuration and how everything settles in once warmed up. Pressure are going to go up due to heat but as long as you started out at the correct pressure you should be OK. There are many years of engineering, mistakes, improvements and research getting you down the road. You can either trust it or head on out on your own. Just keep in mind if you make a mistake the results can be ugly.

And of my scenarios -
1. Hot Side - leave them alone. They will balance back out once cool.
2. Altitude Change - Pressures will be above minimum when you arrive at Pismo due to heat but you probably get a 3AM low pressure alarm IF you reduced pressure while up on the mountain. It's about a 10 PSI change.
3. Air Temp Changes - Much the same as the altitude change. Above minimum while on the move but below once cold.

Tires are pretty amazing considering what we put them thru and the service they provide even after the abuse. But there are limits and a big preventable tire killer is low pressure for the load regardless of is the tire is rolling or sitting still. As long as the pressure is above the limit for the load at any given moment you'll be OK. Be it 3AM sound asleep in the campsite or high noon at 60 MPH crossing the bottom of Death Valley in July.

Now this is just my opinion and is based on what I do for a living, but always go with the psi on the sticker where your gvw stickers are, the tire manufacturers take into consideration about thermal exspansion and constriction and ride and fuel mpg and setting your tire pressures to what they recommend cold is the best thing to do as this allows for expansion when hot/cold with out damaging the tire, over or under inflating will cause premature tire wear as well as void any tire warranty.

[ducksface]

The TPMS is a notification device if used correctly.
It needn't be watched or chased or hand wrang over.
It'll tell you of a blow out, it'll tell you of low pressure, it'll tell you of high temp and high pressure.

If anyone is using it as a source of worry, don't.
Let it holler when it thinks you need to know something.
Pay little daily attention to it.

[blw2]

I agree with duckface...except to add I check it at the start of every trip...after stoppinbg for lunch, etc... just to make sure nothing leaked down while parked.

A couple summers ago we did a trip ot to Grand Canyon. I had my TPMS set to an over pressure alarmat some percentage over teh set point. I don't know the number off hand, but it was teh percetage they suggested I believe. ANyway...no problems, ever, till that trip.

out there in the desert it would get cool at night. So cool that the day would start with very low pressure...so I aired them up. Then later in the day, the temps would of course rocket, increasing both the temp and pressure of teh tire... I kept getting over pressure alarms...so I'd pull over, let a little air out....then it would be low the next morning.

I eventually figured out that I should have just increased the alarm point and left the pressure set for the morning temps....but I figured that out too late. and out on the road I was never able to get the pressures set exactly where I wanted them the rest of the trip. I fought them the whole way! oh well, Live and learn....

[Bob Denman]

Pick a tire pressure (Whatever you, the experts, your friends, the manufacturers, and the kid next door can agree on ); and then just always check your tire pressures when things are "cold"...
What does that mean?
Before you start driving on them: that's all!

[lwmcguire]

Originally Posted by apr67

My answers based on my tire rules. These are mine, you are welcome to have your own opinion.

#1. No you do not adjust tire pressures when hot. (rule A)

#2. 10,000 feet to sea level would be a 10psi change. If you had set tire pressures at 10k you would want to inflate the tire an extra 10psi before you left. However as long as tire pressures never went below the psi required for the weight on your tires, you are fine. (rule B)

#3. If you do not rest during all that time, and tire pressures were set in 50 degree air, you are fine. If you do rest see rule D of tires.

Rules of tires.
A. Only adjust tire pressures on a cold tire.
B. If a tire has less air than in needs at any point in time, adjust the air to its proper psi. This is not considered adjusting.
C. PSI is a function of load and tire design. Understand your weight and the load carrying vs PSI settings of your tires.
D. Always check and adjust tire pressure at the start of driving.
E. A slightly over pressure tire is much safer than a slightly under pressure tire.

You nailed it big time

[Lt Keefer]

It seems to me that TPMS is a way of shifting responsibility for tire problems from the manufacturer to the consumer. I set my pressures based on the weight of my coach and then forget about it. I thump the tires every morning during a trip and then go about my business. There are too many things that could go wrong during a drive, it is a Thor after all, that if I thought about any of them very much I wouldn't even get out of the driveway.

[phoeg]

Originally Posted by GTStang

My 2017 Hurricane 34f has both the front and rear pressure at 95psi. I run about 10psi lower for handling. Does anybody else run the recommended tire pressure of 95psi for there unit?

Yes. I have a 2016 34F and start the day cold at 95 PSI. I chimed in down the line as the posts helped me decide on that method. And I learned to not obsess on the pressures, but just monitor.

My TPMS tells me odd things. Sometimes the inner rear tires will give a high pressure alert. (I set the upper limit per TPMS unit suggestion.) so it shows an over pressure but the temperatures are usually the same as the others within about 2°. They’re often cooler but show over pressure. They usually top out and that’s it. So, I quit worrying. If I get a high pressure alert and high temp, I check it out. Of course, a sudden drop will get my attention.

But yes, I start cold at 95 PSI.