Jump to content
akadeadeye

Tire Pressure & Altitude

Recommended Posts

Going from 1,100 ft. to 8,000-9,500 feet and temps from 90's to 40's lowered my tire pressures 5 to 8 psi. Should I adjust to the pressures I usually carry?

 

Don
 

Share this post


Link to post
Share on other sites

The trick is to inflate to 10% over your minimum air pressure as listed in the load/inflation chart. This eliminates the situation you have now, according to Tireman9. As long as your tire pressures are above minimum, no worries.

Personally, I use the tire pressures listed on the Federal Tire Placard inside the vehicle, and never have to be concerned about altitude or temperature.

 

Share this post


Link to post
Share on other sites

Don,

The VAST majority of the drop in PSI was because of temperature.  Altitude has very little effect. 

 

And, yes, if you will be operating the coach in cold conditions, you will need to inflate the tires to the correct PSI for your load.

Going from Texas summer heat to winter driving, I always have to add air.

Share this post


Link to post
Share on other sites

As you go higher or lower in altitude the pressure will increase or decrease 0.48 psi and the PSI will Increase/decrease 2.0 psi for every 10 degrees of temperature change.

Let's assume your max tire pressure is 110 psi and your minimum load weight pressure is 90 psi. A fudge factor of 10 psi would make the minimum load weight 100 psi.  If you go from sea level to 10,000 feet altitude you would raise 4.8 psi and with the 90 to 40 degree change in temperature you would drop 10 psi for an overall psi change of 5.2 psi.

With the fudge factor of 10 psi you would still be within your minimum required load pressure.  You can do the math for the inverse situation.  I always set my tire pressure between the max the tire allows and the minimum required for the load.  If you do not have the four corner weights then run max tire pressure allowed and be safe, only adjusting as needed when you get to your destination. There are other scenarios, I'll bet, and the closer the minimum and maximum tire pressures are, the less of a fudge factor is available.

Tireman9, Roger, please correct me if  this is not correct and I'll ask for the post to be removed.

Share this post


Link to post
Share on other sites
26 minutes ago, wayne77590 said:

I'll ask for the post to be removed.

No need for that, you can always go back and correct it by using "edit". 

Share this post


Link to post
Share on other sites
23 minutes ago, wayne77590 said:

Edit is only good for so long then it goes away

HUH? I've used edit for years and never seen it go away, unless it contained something that Brett didn't like.:wub:

Share this post


Link to post
Share on other sites
On 9/18/2019 at 8:39 AM, wolfe10 said:

Don,

The VAST majority of the drop in PSI was because of temperature.  Altitude has very little effect. 

 

And, yes, if you will be operating the coach in cold conditions, you will need to inflate the tires to the correct PSI for your load.

Going from Texas summer heat to winter driving, I always have to add air.

Thanks Brett.

And, thanks to the other replies.

 

Don

Share this post


Link to post
Share on other sites
On 9/18/2019 at 12:31 PM, wayne77590 said:

Guess I never really paid attention to it. Must be because I'm right all the time.👹

What is the other half's opinion? :rolleyes: I know what mine would say about me.:ph34r:

Share this post


Link to post
Share on other sites

I'm always right. If you don't believe me just ask me.

Up in altitude pressure increases by 0.48 psi for every 1000 feet of altitude change. Down in altitude, the reverse,

Up in altitude pressure decreases by 2% for every 10 degrees of temperature change. Down in altitude it increases.

The math is fairly simple.

Share this post


Link to post
Share on other sites
On 9/18/2019 at 11:17 AM, wayne77590 said:

As you go higher or lower in altitude the pressure will increase or decrease 0.48 psi and the PSI will Increase/decrease 2.0 psi for every 10 degrees of temperature change.

Let's assume your max tire pressure is 110 psi and your minimum load weight pressure is 90 psi. A fudge factor of 10 psi would make the minimum load weight 100 psi.  If you go from sea level to 10,000 feet altitude you would raise 4.8 psi and with the 90 to 40 degree change in temperature you would drop 10 psi for an overall psi change of 5.2 psi.

With the fudge factor of 10 psi you would still be within your minimum required load pressure.  You can do the math for the inverse situation.  I always set my tire pressure between the max the tire allows and the minimum required for the load.  If you do not have the four corner weights then run max tire pressure allowed and be safe, only adjusting as needed when you get to your destination. There are other scenarios, I'll bet, and the closer the minimum and maximum tire pressures are, the less of a fudge factor is available.

Tireman9, Roger, please correct me if  this is not correct and I'll ask for the post to be removed.

Sounds good to me.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...