Tire Pressure Vs. Ambient

[bluwtr49]

I recently found that adjusting our tires to the cold inflation temperature base on the local ambient may not be the correct way to do this. Based on this info, the ambient temp for setting tire pressure is always 65F and they are than adjusted upwards base on local ambient.

This was a surprise to me and would suggest that many are running their tires under inflated.

Tire Pressue vs Ambient

Something to consider. Me, I'm going to follow this guide.

[jadatis]

In Holland Europe where I live, there is a foundation "band op spanning" who fills right pressure to car tires .
They also adyust recalculate the pressure for ambiënt temp then 18degrC/65degr F.

And that also means for lower ambiënt temp , lower pressure then adviced by car-maker.

What the article writes, is that for higher temp its always save to highen up the pressure as given in list, but tire- and car- makers do not prescribe lower pressure for lower temp.

Here also the discrepance between regulations and rules, and laws of nature.
To law of nature this idea given is logical.

And if you measure at 32 degrees a lower ( cold) pressure that belongs to the pressure in the list of article , you probably wont fill up. And nature proofes that your tires wont damage.

At colder ambiënt temp the deflection of tire is more so more heatproduction, but also the cooling down is more because of the larger temp difference between inside and outside tire.

I am busy now figuring this out , if that more cooling down is then in line with the more heatproduction.
Will use that list for it so I dont have to calculate it myself.

[Effy]

JumboJet wrote:
As for me, I check air pressure before leaving on a trip. I then use my "Ryan Newman - NASCAR" microscopic drill to drill a bleeder hole in the tire. As the tire warms up, the increased pressure bleeds off through the microscopic hole and I arrive at my destination with the same tire air pressure as I started with.

I have various diameter microscopic drill bits based on the beginning and ending temperatures planned for my trip.

I will send you my chart and you may want to adopt my tire pressure solution.

After all, Ryan Newman is a NASCAR winner - occasionally.

we really need a like button on this forum.

[JumboJet]

As for me, I check air pressure before leaving on a trip. I then use my "Ryan Newman - NASCAR" microscopic drill to drill a bleeder hole in the tire. As the tire warms up, the increased pressure bleeds off through the microscopic hole and I arrive at my destination with the same tire air pressure as I started with.

I have various diameter microscopic drill bits based on the beginning and ending temperatures planned for my trip.

I will send you my chart and you may want to adopt my tire pressure solution.

After all, Ryan Newman is a NASCAR winner - occasionally. 🙂

BTW - the above was all in fun. That scenario actually played out and cost RCR $250,000 plus suspensions and probation.

I check and set pressure before I leave and will do a ball bat 'thump' test and also do a temperature test with an infrared thermometer during stops.

[rgatijnet1]

holstein13 wrote:

rgatijnet1 wrote:

In my case, since I checked my tires when cold, before I got on the road, (This may not be a convenient thing to do based upon your location or time of day.) if I noticed a tire that was LOW at the first rest stop, I would know I have a problem with that tire. (I'm not sure how you would "know" you have a problem. I think you would ASSUME you have a problem. But I certainly would not ASSUME I had a problem. Maybe some kid just let some air out.)I may put air in it to get to a service center, but I certainly would not ASSUME that the tire was now safe and would remain safe/perfect the next day.(Sounds to me like you are making other assumptions. Not me. I'll inspect the tire and keep an eye on the tire pressure monitor and I'll figure out using facts whether or not I have a problem.) If it was a dual, I would also be concerned about the other dual that had to take up the additional weight to compensate for the tire that was low.

Is this the same monitor that did not warn you the tire was losing air until you noticed it at the rest stop? :B

[wolfe10]

Executive wrote:
How are you gonna get OUT of Texas without a BOAT.....:h....Dennis

Oh, but we DO have a boat-- Catalina 350. About 1.5 miles from the house. No flooding here-- water just drains into the bay, then Gulf.

Have not filled up the Gulf yet.

[holstein13]

rgatijnet1 wrote:

In my case, since I checked my tires when cold, before I got on the road, (This may not be a convenient thing to do based upon your location or time of day.) if I noticed a tire that was LOW at the first rest stop, I would know I have a problem with that tire. (I'm not sure how you would "know" you have a problem. I think you would ASSUME you have a problem. But I certainly would not ASSUME I had a problem. Maybe some kid just let some air out.)I may put air in it to get to a service center, but I certainly would not ASSUME that the tire was now safe and would remain safe/perfect the next day.(Sounds to me like you are making other assumptions. Not me. I'll inspect the tire and keep an eye on the tire pressure monitor and I'll figure out using facts whether or not I have a problem.) If it was a dual, I would also be concerned about the other dual that had to take up the additional weight to compensate for the tire that was low.

[Effy]

The point I think is really this; instructions are to check psi "cold". Well, define cold. Since everyone on this forum (unless we are next door) has a different ambient temperature, cold is relative. For the purposes of documentation, cold is defined by tire manufacturers as a static value of 65. I won't guess why they picked 65 but that's what it is. The chart was talking about a moving scale. So 85 PSI at 65 deg F would follow a curve to more PSI the higher the ambient temp. This is not new science it's just a relative curve based on a static temp vs real world variant temp. In the grand scheme of things, tires are designed to run on a wide range of temps and PSI safely (because of variant factors). So , this is all a lot of air.

[holstein13]

Ductape wrote:
You guys are talking past each other without connecting. I think we all agree a tire warmed from use needs more air pressure. That's not the premise of the article cited.

That article claims resting (COLD) pressure should vary depending on ambient. Only true if you live in a universe where gravity is affected by temperature.

No disagreement with that either. COLD can be 45 degrees, 65 degrees or 85 degrees based upon where you are. My system adjusts for all those COLD temperatures and I don't need to fool with it based upon temperature. Once set, I'm good unless air leaks out.

[holstein13]

Kaz wrote:
I'm not sure why this seems controversial: the science is sound. For example, here's what Roger Marble says on RV Tire Safety: "As you work through my earlier posts you will see the general guideline for pressure increase of about 2 percent for every 10°F, so if you set your cold pressure to 80 psi in Oklahoma City in November and it's 45°F you may see your cold pressure has increased to 86 psi in Phoenix the next morning when it is 85°F." Or running it the other way, if you set your cold pressure at 86 psi at 85°F, the cold pressure would be 80 psi at 45°F. So, the question is, if the cold pressure is right in Phoenix, should you add air when you get to Oklahoma City?

X2, this is reality. Tire pressures rise with temperature. Who's kidding who? Should we ignore that scientific fact, or should we factor that into our decisions when we fill our tires?

I like to go with reality, it works out much nicer for me. I'll fill my tires at the end of the day with extra heat adjusted pressure and the next day they are perfect at 65 degrees. Reality works great for me.

The only tricky part is in the winter when temps are in the 20s and 30s. But if we are filling our tires in the 20s, maybe there is something else that's wrong. Maybe we should move south.

[Ductape]

You guys are talking past each other without connecting. I think we all agree a tire warmed from use needs more air pressure. That's not the premise of the article cited.

That article claims resting (COLD) pressure should vary depending on ambient. Only true if you live in a universe where gravity is affected by temperature.

[rgatijnet1]

holstein13 wrote:


What happens when you get to the rest stop and notice your tires look a little low? Did someone fool with your tire? What do you do? In your case, I guess you'll sit there and wait until morning to fill them. After all, you don't want to "out think" any tire engineers, do you? In my case, I'll fill it to the proper heat adjusted pressure and move on, safe in the knowledge that the pressures will be perfect and will remain perfect even the next day.

You may fill your tires in accordance with good engineering theory. I fill mine in accordance with good engineering reality.

In my case, since I checked my tires when cold, before I got on the road, if I noticed a tire that was LOW at the first rest stop, I would know I have a problem with that tire. I may put air in it to get to a service center, but I certainly would not ASSUME that the tire was now safe and would remain safe/perfect the next day. If it was a dual, I would also be concerned about the other dual that had to take up the additional weight to compensate for the tire that was low.

[holstein13]

Executive wrote:
Always wise to out think the tire engineers....:S....

I've never seen anything anywhere that encourages one to fill a HOT tire...but of course, I've never "skidded to a halt in 100 degree weather" either...:W....Dennis

Nobody is encouraging anyone to fill a HOT tire, but with this technology, you can. Let's face reality. It's not always convenient or even practical to fill your tires when they are cold.

What happens when you get to the rest stop and notice your tires look a little low? Did someone fool with your tire? What do you do? In your case, I guess you'll sit there and wait until morning to fill them. After all, you don't want to "out think" any tire engineers, do you? In my case, I'll fill it to the proper heat adjusted pressure and move on, safe in the knowledge that the pressures will be perfect and will remain perfect even the next day.

You may fill your tires in accordance with good engineering theory. I fill mine in accordance with good engineering reality.

[Kaz]

bluwtr49 wrote:
I recently found that adjusting our tires to the cold inflation temperature base on the local ambient may not be the correct way to do this. Based on this info, the ambient temp for setting tire pressure is always 65F and they are than adjusted upwards base on local ambient.

This was a surprise to me and would suggest that many are running their tires under inflated.

Tire Pressue vs Ambient

Something to consider. Me, I'm going to follow this guide.

I'm not sure why this seems controversial: the science is sound. For example, here's what Roger Marble says on RV Tire Safety: "As you work through my earlier posts you will see the general guideline for pressure increase of about 2 percent for every 10°F, so if you set your cold pressure to 80 psi in Oklahoma City in November and it's 45°F you may see your cold pressure has increased to 86 psi in Phoenix the next morning when it is 85°F." Or running it the other way, if you set your cold pressure at 86 psi at 85°F, the cold pressure would be 80 psi at 45°F. So, the question is, if the cold pressure is right in Phoenix, should you add air when you get to Oklahoma City?

I'll send a message to Marble as to whether one is supposed to chase the pressure/temperature curve all over the place every morning, or just ignore the temperature correction and figure it's close enough for government work. (I've always assumed one can ignore the temperature correction, but you know what they say about "assume...")

Skip

[rgatijnet1]

Executive wrote:

holstein13 wrote:
This is exactly the way Triptek programs their tire pressure sensors in my RV. It's based on temperature and pressure so if the temperature rises, the TPMS system calls for higher pressures in the tires. The base temperature is at 65 degrees.

I love the system because it tells me if I'm above or below the ideal pressure and I can inflate my tires at any time. I just turn to the proper tire screen and fill or release as needed. That's a huge benefit for me. I don't have to wait until morning to inflate my tires. I can inflate them first thing in the morning, at noon when the sun is shining on them or after skidding to a halt in 100 degree weather. It doesn't matter. My TPMS calculates it for me.

Once you've had the pleasure of getting the heat adjusted tire pressures, you won't want to go back to the old way of checking pressures in the morning only.

Always wise to out think the tire engineers....:S....

I've never seen anything anywhere that encourages one to fill a HOT tire...but of course, I've never "skidded to a halt in 100 degree weather" either...:W....Dennis

And yet, whenever someone has a tire problem, they come to this forum to blame the tire manufacturer and swear that they maintained their tires EXACTLY according to the manufacturers recommendations. :B

[Executive45]

holstein13 wrote:
This is exactly the way Triptek programs their tire pressure sensors in my RV. It's based on temperature and pressure so if the temperature rises, the TPMS system calls for higher pressures in the tires. The base temperature is at 65 degrees.

I love the system because it tells me if I'm above or below the ideal pressure and I can inflate my tires at any time. I just turn to the proper tire screen and fill or release as needed. That's a huge benefit for me. I don't have to wait until morning to inflate my tires. I can inflate them first thing in the morning, at noon when the sun is shining on them or after skidding to a halt in 100 degree weather. It doesn't matter. My TPMS calculates it for me.

Once you've had the pleasure of getting the heat adjusted tire pressures, you won't want to go back to the old way of checking pressures in the morning only.

Always wise to out think the tire engineers....:S....

I've never seen anything anywhere that encourages one to fill a HOT tire...but of course, I've never "skidded to a halt in 100 degree weather" either...:W....Dennis