Is your Air gauge accurate?

[Hastey]

Rex, first let me thank you for your service and second, welcome home.

On this inflation business, I am thinking or of the opinion that the air pressure should be checked on the trailer and the tow vehicle "after" everything is hooked up and ready to roll. Then when you are done towing and the tires have cooled off readjust the tire pressure of the tow vehicle. Does that make sense?

I think it's a matter of opinion when you get down to it. I was just thought that way. Check your tires empty then add the load. That was always one of the top items on the PMCS checklist before you ever started making smoke. But, there were times that there would be a dozer or other piece of heavy junk loaded a couple of days before. So really we did it both ways. Now to be really honest Most of the time we just kicked the tires on the trailers and went on. We cared more about the Freightliners tires than anything, especially the steering axle. Our tires were provided by the lowest bidder and we could use recaps on anything but the front tires on the steering axle. P.O.S. tires and I've scattered more rubber up and down the road than you can believe and especially after the temps got over 90. Nothing like trying to change a flat on a trailer and it's so hot that the weight of the dozer/trailer is shoving your jack thru the asphalt on the shoulder of I-40. Good Times!

 

[wingfoot]

Jeff, you know that's an interesting question. My knee-jerk answer would be...Inflate your tires, fully loaded and not hitched up. Inflate to the tire specifications "cold". Cold would mean before you start your trip. The manufactures will usually take into consideration there are fluctuating ambient temperatures and factor in a +10/-10 percent tolerance. If you have ever checked a "hot" (running temp) you will get a higher temperature reading. All that being said, it is my opinion to always check your tires prior to towing...unhitched. There, as I'm sure you know, variables to be taken into consideration. Ambient temperature and elevation as we travel.

But that's a great question...

Here is an addendum to this question brought up by Jeff above. I checked with the Commercial Truck Tire Engineers at Goodyear Tire and Rubber about before load/after load. They said, "always check air pressures before you load." The PSI will not change appreciatively. He kinda laughed at me (I know this guy) and said "The load will not MAKE AIR. If your PSI increases something is wrong". "If you doubt this, check your tires with no load..Then check them after you're loaded".

I for one, am going to do this..Not yet satisfied, gotta be shown..

BTW, he did say you possibly could get a insignificant non appreciable difference.

 

[Hastey]

Here is an addendum to this question brought up by Jeff above. I checked with the Commercial Engineers at Goodyear Tire and Rubber about before load/after load. They said, "always check air pressures before you load." The PSI will not change appreciatively. He kinda laughed at me (I know this guy) and said "The load will not MAKE AIR. If your PSI increases something is wrong". "If you doubt this, check your tires with no load..Then check them after you're loaded".

I for one, am going to do this..Not yet satisfied, gotta be shown..

BTW, he did say you possibly could get a insignificant non appreciable difference.

I'm torn between the two. I never tested it but my first thought is if you inflate a basket ball and then drive on it the pressure will increase and bust the ball?????

 

[jimtoo]

I was taught or told by others in the late 50's..60's while HD trucking to always check pressure cold. Then later in the car and truck repair and sales,, check the tires cold.. even by a Goodyear Tire Engineer in 1972,,(another story).
If the tires are checked cold and truck empty and then you load the truck,, you might see a very small increase. On the airbags (riderights or what ever) checked before loading (10psi) the trailer on the hitch... hitch it up and I have about 30psi. But the reason you see so much difference in increase in pressure from tire to airbag is the amount of volume difference. Stop and think,,, put 5000# on 1 cubic foot of space (airbag) against 5000# on 10 cubic feet of space, (tire). Which is going to show more pressure increase? I always check cold... and may stop checking completely.

Did you ever notice.. every time someone has a blowout that it is always said,,, "I checked pressure just before I departed",,, or "pressure was checked yesterday",,,"had them checked 15 minutes ago",,, no I am not pointing fingers at anyone. But it happened to me a couple of weeks ago...I checked both front tires because they looked low,,, truck was in dirt and both had between 65--70#.... Truck had been setting 3 days.... drove it 10 miles, with no load..not over 70mph...temp about 95*,,, stopped,, got out and walked around the front and was just beside the right front tire when it EXPLODED. I mean it actually blew up,, right across the tread area,,, not sidewall. The amazing thing is there was none,, not any.. indication of a bad tire like shimmy,,, vibration,, or anything like that and when I checked the tire before I departed I did not see any sign of bubble or cracks on the outside or tread area that was visible. This tire was a Michelin XPS,,,maybe 20K miles on it,, no unusual wear. Now we did travel some pretty bad roads on the way to Goshen this year and had some really bad pavement holes... I am thinking the tire was damaged by this.. but was so surprised at the fact no visible damage, no feel of damage in driving and no loss of air pressure prior to the blowout. Just glad I was not on the road with the 5er hooked up. Ohh,,, Yea ,,Good Sam Road service...I was on the phone 1:30 min..G/S was looking for service... finally,, service man came from about 500 feet away...total time about 2 hours.

So,,, it looks to me like if you check your tires... watch out for a blowout.... I have a couple of air gauges I think I will give away.

 

[wingfoot]

Good post Jim, I agree with everything you posted..

Larry

 

[Hastey]

I was taught or told by others in the late 50's..60's while HD trucking to always check pressure cold. Then later in the car and truck repair and sales,, check the tires cold.. even by a Goodyear Tire Engineer in 1972,,(another story).
If the tires are checked cold and truck empty and then you load the truck,, you might see a very small increase. On the airbags (riderights or what ever) checked before loading (10psi) the trailer on the hitch... hitch it up and I have about 30psi. But the reason you see so much difference in increase in pressure from tire to airbag is the amount of volume difference. Stop and think,,, put 5000# on 1 cubic foot of space (airbag) against 5000# on 10 cubic feet of space, (tire). Which is going to show more pressure increase? I always check cold... and may stop checking completely.

Did you ever notice.. every time someone has a blowout that it is always said,,, "I checked pressure just before I departed",,, or "pressure was checked yesterday",,,"had them checked 15 minutes ago",,, no I am not pointing fingers at anyone. But it happened to me a couple of weeks ago...I checked both front tires because they looked low,,, truck was in dirt and both had between 65--70#.... Truck had been setting 3 days.... drove it 10 miles, with no load..not over 70mph...temp about 95*,,, stopped,, got out and walked around the front and was just beside the right front tire when it EXPLODED. I mean it actually blew up,, right across the tread area,,, not sidewall. The amazing thing is there was none,, not any.. indication of a bad tire like shimmy,,, vibration,, or anything like that and when I checked the tire before I departed I did not see any sign of bubble or cracks on the outside or tread area that was visible. This tire was a Michelin XPS,,,maybe 20K miles on it,, no unusual wear. Now we did travel some pretty bad roads on the way to Goshen this year and had some really bad pavement holes... I am thinking the tire was damaged by this.. but was so surprised at the fact no visible damage, no feel of damage in driving and no loss of air pressure prior to the blowout. Just glad I was not on the road with the 5er hooked up. Ohh,,, Yea ,,Good Sam Road service...I was on the phone 1:30 min..G/S was looking for service... finally,, service man came from about 500 feet away...total time about 2 hours.

So,,, it looks to me like if you check your tires... watch out for a blowout.... I have a couple of air gauges I think I will give away.

I never thought about it Jim but You are right. I wonder if driving low on the tires breaks them down and then when you pressure them up you have problems

 

[jimtoo]

I never thought about it Jim but You are right. I wonder if driving low on the tires breaks them down and then when you pressure them up you have problems

I would think driving with low air pressure would cause more flex which,, in my way of thinking, could cause more damage over time due to all the flex. It will definitely cause more heat build up which is very damaging to the tire.

Jim M

 

[olcoon]

Here is something I've been wondering about. The last time I was hooked to the 5er, I checked all tires in the morning before I left, and had them all aired up to 80 psi. It was in the neighborhood of 40 degrees that morning.. As I drove along, and the day warmed up, to over 75 degrees, my tire pressure also increased, to around 95 psi. I would think this would be an over inflated tire, and I should let some air out when they get that high, as an over inflated tire can also cause damage. Anyone got an "expert" opinion?

 

[jimtoo]

First I am sure the manufactures build the tires to handle the normal increase in pressure due to heat.

Now,, Let’s try this country boy explanation or demonstration of “flex = heat”. Get a wire coat hanger, cut a piece about 10—12 inches long. Place one end in a vice or someplace secure. Then hold the other and start bending it back and forth at just above the jaws of the vice so it is bending in the same place each time. Move it about 120*, (60* each side if straight up) do this about 10—12 times fairly fast, in like 10 seconds. Now,,, put your fingers on the place where it was being bent, just above the vice jaws… careful,, it will be warm or even hot. Now take another piece of wire, do the same only do not bend it as much…say just 40*,, (20* each side of straight up)…,,, guess what…. None or very little heat. This is why our tires need to be aired up to max rated pressure.
Less Flex = Less Heat.

Jim M

 

[jnbhobe]

Well said Jim; but now I need a break after all that work.

 

[jmgratz]

As I have posted before, when attending a tire seminar I asked the same question to the presenter who was a retired (after 40 years) GoodYear Tire Design/Engineer. He told me the max air pressure is a COLD pressure and the tire is designed for the natural INCREASE in pressure. He stated that even a change in elevation is not enough to cause problems unless you are flying an airplane. That is why airplanes use nitrogen. But for car tires if you let out air after the tire heats up to the max air pressure the tire will be UNDERINFLATED which caused damage due to the heat generated. So after hearing that I just check the pressure and inflate them to the recommended COLD pressure and forget about it. With the Doran Tire Pressure Monitoring System (TPMS) I can start the day at 110 psi (GoodYear G614) and as I drive I have seen the pressure increase to as much as 126 (on the sun side) and 122 on the shady side. This is on a very hot summer day. Normally it will go from 110 psi cold to about 119 as we drive. Hope this info helps. BTW if you ever get a chance to attend an Escapee Escapade and attend the RVers BOOT CAMP I would highly recommend it. There is just a ton of great information you get even if you are a seasoned RVer.

 

[lwmcguir]

I agree always check and ajust the air pressure when the tires are cold and prefferably early in the morning befor they have set in the sun. After that watch the temperature when traveling. If you have one or more that are consistently quite a bit hotter they are probably overloaded or you may even have an alignment issue. I have noticed our 17.5's run a lot cooler than the G614 16's did under the same conditions.

 

[wingfoot]

As I have posted before, when attending a tire seminar I asked the same question to the presenter who was a retired (after 40 years) GoodYear Tire Design/Engineer. He told me the max air pressure is a COLD pressure and the tire is designed for the natural INCREASE in pressure. He stated that even a change in elevation is not enough to cause problems unless you are flying an airplane. That is why airplanes use nitrogen. But for car tires if you let out air after the tire heats up to the max air pressure the tire will be UNDERINFLATED which caused damage due to the heat generated. So after hearing that I just check the pressure and inflate them to the recommended COLD pressure and forget about it. With the Doran Tire Pressure Monitoring System (TPMS) I can start the day at 110 psi (GoodYear G614) and as I drive I have seen the pressure increase to as much as 126 (on the sun side) and 122 on the shady side. This is on a very hot summer day. Normally it will go from 110 psi cold to about 119 as we drive. Hope this info helps. BTW if you ever get a chance to attend an Escapee Escapade and attend the RVers BOOT CAMP I would highly recommend it. There is just a ton of great information you get even if you are a seasoned RVer.

Great post Jim...just out of curiosity, did you get the design/engineer's name..I too retired with Goodyear after 37 years and knew a lot of people in that department...Just curious, might know this guy..

Larry

 

[wingfoot]

BTW, I thought I would show you guys a High Tech. commercial carrier driver's air-gauge.
For those that don't know what this is...It's called a "Bump" stick. You'll not find a trucker without one. They will check their rigs tires by "bumping'' them with this stick..A seasoned trucker can detect a low tire by sound.

Also, I guess in a pinch it could be used as a self protection tool.

 

[Hastey]

BTW, I thought I would show you guys a High Tech. commercial carrier driver's air-gauge.
For those that don't know what this is...It's called a "Bump" stick. You'll not find a trucker without one. They will check their rigs tire by "bumping'' them with this stick..A seasoned trucker can detect a low tire by sound.

Also, I guess in a pinch it could be used as a self protection tool.


View attachment 16121

That's what I'm talkin about.

 

[jmgratz]

Great post Jim...just out of curiosity, did you get the design/engineer's name..I too retired with Goodyear after 37 years and knew a lot of people in that department...Just curious, might know this guy..

Larry

I cannot remember his name but he gave the seminar at the RVers Boot Camp at the Escapade in Sedala Mo 2 or 3 years ago.

 

[wingfoot]

No problem...I knew it would be a long shot. Thanks for replying though.

Larry