Know your equipment - true story

[Jim Edgerly]

So I go out this spring and check my tire pressure. I have to admit I don't check it as often as I should. I normally just pull up to the service station, put my $1 in, and pump my tires up to 50psi without knowing where I started from.

But every spring I dig out my old "pencil style" air gauge and check the pressure first thing. Again, same as last year, only 42psi. My tires seem pretty consistent at losing those 8 lbs over the winter just sitting there for 6 months. Drag my ass, and camper, down to the service station, pay my $1, and pump it back up to 50psi, as measured on the pump gauge.

So by now I'm thinking I should be a little bit more responsible and check the pressure more often, and top them off. So I start my quest to find the right 12V pump to carry with me camping. I buy one at HomeDepot, bring it home, and start pumping up my first tire, trying to get it to go above 50psi so I will know it works OK and will suit my needs. It runs for about 30 seconds then dies. OK, that piece of $30 crap goes back to HomeDepot for my money back, and will pay more next time...but that is another story for another time.

I figure I might have put a little more air in the tire than the 50 maximum, so I get out my old trusted pencil style air gauge and check it again. 42 freaking pounds again, just like the first of the season measurement, just like every measurement these tires ever give me. I'm starting to wonder if these tires just leak anything over 42 pounds and I just need new tires. Then it dawns on me...

I take the white bar sticking out of my pencil gauge and pull on it. DAMN, it won't pull out past 42 pounds! It's a damn "car" tire gauge that should never have a need to exceed 42 pounds. All the times I have driven to a service station to buy air because I only had 42 psi. I sometimes think I am my own worst enemy.

Going to the auto store to pick up a new pressure gauge, one that goes to at least 60psi.

[Dale M.]

Ummm.... What tires and weight requires you to have 50 psi in your tires.... Seems a little high....

Dale

[jeff0520]

Go to ther nearest truck stop. The tire gauge for a tractor trailer goes up to 140 psi. I have the new style super single drive tires on my truck, and they get inflated to 125 psi. They are so big, and the pressure is so high, that you need to pack a lunch when you go to inflate them

[Jim Edgerly]

Ummm.... What tires and weight requires you to have 50 psi in your tires.... Seems a little high....

Dale

I am running special trailer tires, not passenger tires. All (or at least the overwhelming vast majority of) special trailer tire manufactures agree on one thing..."Always inflate trailer tires to the maximum inflation indicated on the sidewall because underinflation is the number one cause of trailer tire failure."

I may get a smoother ride with 40lbs pressure in my tires (maybe not enough to even notice at the expense of less mpg), but if the excessive sidewall flexing causes my tire to fail and my tire blows out and flies apart at highway speeds it's not much of a bargin. I'm going with what the vast majority of trailer tire expert recommend and go at the maximum stated for my tire, which in my case is 50psi. My shocks do a pretty good job of smoothing out the ride. If when these tires reach the end of their stated life I may, or may not, go with passenger tires.

One thing I surely don't want is to have a blow out, be the cause of a major accident, then have the authorities see I intentionally run my tires below the manufacturers recommendations. I carry a lot of insurance, but law suits run ridiculous these days.

[Jim Edgerly]

just get yourself a normal air comperssor and fill up at home!!!!!!!!!!!!!!

Filling up a home sounds good, but like this summer my wife (a school teacher with the summer off) and I are taking the dog on a 3-4 week trip, probably spanning up to 1000 miles before returning home. I would like the ability to check/top off during the trip where needed.

Jim

[Socal Tom]

I run 215/75/15 inch tires they are mudd and snow heavy lts for off road use.

they run 50 pounds of air easly! and they are on my teardrop.

Even if your tires can take 50 psi, doesn't mean they should. Tire pressure should be matched with the load. Too much pressure on a light load results in wearing out the middle of the tire, and a much harsher ride.
This is a chart I came across a few years back to help with many tire pressure/load combinations.


https://lh3.googleusercontent.com/-jyBi ... vs+psi.jpg

The other way to check is to draw a chalk line across the tire and drive a hundred feet or so in a straight line and see where the chalk wore off.
Tom

[Rolly]

A note on tire pressure. Check the rating on your wheels before you buy heavy duty tires and air them to the max. Probably more of a problem on 15 and 16 inch rims. Most of the D rated trailer rims I have checked are rated for 60 psi, many E rated tires are have 85 psi as the max.

Rolly

[Jim Edgerly]

I run 215/75/15 inch tires they are mudd and snow heavy lts for off road use.

they run 50 pounds of air easly! and they are on my teardrop.

Even if your tires can take 50 psi, doesn't mean they should. Tire pressure should be matched with the load. Too much pressure on a light load results in wearing out the middle of the tire, and a much harsher ride.
This is a chart I came across a few years back to help with many tire pressure/load combinations.


https://lh3.googleusercontent.com/-jyBi ... vs+psi.jpg


Tom

I checked the chart...my tires are "Load Range C"...what Load Index does that equate to on your chart? Also, there is no heading on the chart. Is this chart for A) Bias passenger tires...B) Radial passenger tires...C) Bias special trailer tires...D) Radial special trailer tires...E) Bias light truck tires...or F) Radial light truck tires? Without knowing what the chart is for it is hard to determine the likelyhood of the chart being useful for any given tire.

[Dale M.]

About tire pressures.....

For Michelin

Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall

http://www.michelinman.com/tires-101/ti ... QgodMkMAxg

Also

http://www.tirerack.com/tires/tiretech/ ... p?techid=8

Granted the above is about car manufacturers recommendation of tire pressures for a particular tire found on specific car model...

BUT this tells me you inflate tires by what ever application you are using tire for NOT THE MAXIMUM STATED ON TIRE SIDE WALL....

Its all about tire wear NOT about MAX pressure.... IF you have extreme wear in center of tire and lots of good tread on outside edges, you are over inflating tires..... Its also inverse, if you have extreme wear on out side edged of tires and plenty of thread on center of tire you are UNDER INFLATING Tires....

Best tool for gauging tire pressure is a tread depth measurement tool used in conjunction with pressure gauge..



IF not dedicated gauge then....



Dale

[alaska teardrop]

I run 215/75/15 inch tires they are mudd and snow heavy lts for off road use.

they run 50 pounds of air easly! and they are on my teardrop.

Even if your tires can take 50 psi, doesn't mean they should. Tire pressure should be matched with the load. Too much pressure on a light load results in wearing out the middle of the tire, and a much harsher ride.
This is a chart I came across a few years back to help with many tire pressure/load combinations.


https://lh3.googleusercontent.com/-jyBi ... vs+psi.jpg


Tom

I checked the chart...my tires are "Load Range C"...what Load Index does that equate to on your chart? Also, there is no heading on the chart. Is this chart for A) Bias passenger tires...B) Radial passenger tires...C) Bias special trailer tires...D) Radial special trailer tires...E) Bias light truck tires...or F) Radial light truck tires? Without knowing what the chart is for it is hard to determine the likelyhood of the chart being useful for any given tire.

Jim, The load index on the left is on the side of the tire. It is useful in showing the relationship of tire pressure to the actual load rating because you can adjust your tire pressure to the weight of the trailer.

http://www.tirerack.com/tires/tiretech/ ... ?techid=35

Fred

[Jim Edgerly]

I run 215/75/15 inch tires they are mudd and snow heavy lts for off road use.

they run 50 pounds of air easly! and they are on my teardrop.

Even if your tires can take 50 psi, doesn't mean they should. Tire pressure should be matched with the load. Too much pressure on a light load results in wearing out the middle of the tire, and a much harsher ride.
This is a chart I came across a few years back to help with many tire pressure/load combinations.


https://lh3.googleusercontent.com/-jyBi ... vs+psi.jpg


Tom

I checked the chart...my tires are "Load Range C"...what Load Index does that equate to on your chart? Also, there is no heading on the chart. Is this chart for A) Bias passenger tires...B) Radial passenger tires...C) Bias special trailer tires...D) Radial special trailer tires...E) Bias light truck tires...or F) Radial light truck tires? Without knowing what the chart is for it is hard to determine the likelyhood of the chart being useful for any given tire.

Jim, The load index on the left is on the side of the tire. It is useful in showing the relationship of tire pressure to the actual load rating because you can adjust your tire pressure to the weight of the trailer.

http://www.tirerack.com/tires/tiretech/ ... ?techid=35

Fred

My "car" tire shows 96H...my special trailer tire shows "Load Range C"...there is not a "load index" on them so I have to assume your chart is for "car" tires only and not applicable to "Special Trailer" tires. Car tires and Special Trailer tires ARE made different for different purposes and with different needs.

Special Trailer tire designers and manufactures say they have designed the tire to be used at the maximum inflation as stated on the tire sidewall...this is where maximum tread life and safety occur. From what I read a tire underinflated by 10psi (20%) can lead to tire failure, in addition to reducing tread life by as much as 25%, and decreasing mpg as well.

According to trailer tire designers/manufactures reduced sidewall flex is absolutely CRUCIAL for safety, so ST tires feature stiffer sidewalls, especially in the lower section which reduces sidewall flexing causing the trailer to track straighter, diminishes the risk of trailer sway and lessens the risk of sidewall puncture and blowout. Flexing in the sidewall produces heat in the sidewall and tread which can quickly cause tire degradation or blowout. Excessive heat caused by under inflation is the number one cause of trailer tire failure.

In my heart I have to follow what the Special Trailer tire designer/manufacturer says is right for their tires vs what a car tire designer/manufacturer says is right for their tires. If I were running car tires on my trailer I would follow their advice, but I am not.

[Jim Edgerly]

About tire pressures.....

For Michelin

Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall

Granted the above is about car manufacturers recommendation of tire pressures for a particular tire found on specific car model...

BUT this tells me you inflate tires by what ever application you are using tire for NOT THE MAXIMUM STATED ON TIRE SIDE WALL....

Dale

Dale, even if the special trailer tire manufacture states that the trailer tire was designed only to be used at the maximum stated on the tire, and NOT at reduced tire pressures? The tire was designed to be run only at the max pressure stated...anything less than and all the design work put into making that tire safe is out the window.

I, in good conscience, cannot say that I know more about the specific tires on my trailer than the engineer who designed them. If he/she says that were designed to be run only at 50psi then I have to go by that. If I had the knowledge/degree that he/she has, the experience, and the computer software they used, then I might venture into thinking that I know more, or at least as much, about their tires than they do. At that point I might decide to change the air pressure...but alas, I don't.

And nothing personal, but I don't think there is anybody in here that can convince me that they know more than the specific engineer who designed the specific tires on my teardrop.

[jstrubberg]

Jim;

I have to admit, my responses to this topic were based 100% on both recommendations for and personal use of passenger car and light truck tires.

I can't imagine how the tire industry can think that it's desirable for a passenger car tire sidewall to flex and a trailer tire sidewall not to flex, but you are correct, they absolutely do recommend running max pressure in trailer tires.


Folks, please, PLEASE recognize this is not the case with passenger car and light truck tires! No manufacturer, not one, recommends running max pressure in a car or truck tire unless you are at max load. Every car has a placard, usually on the drivers side door post, with recommended tire pressures. The number on the side of the tire is NOT the recommended pressure!

Jim, I'm sorry for derailing your thread. You were right, I was wrong. I saw what I wanted to see, not what you wrote.

[alaska teardrop]

Jim, I think you're absolutely right about your tires, as your research shows. No argument. I personally use all-season radial car tires for a safe, smooth & stable ride.

Fred

[Socal Tom]

Jim;

I have to admit, my responses to this topic were based 100% on both recommendations for and personal use of passenger car and light truck tires.

I can't imagine how the tire industry can think that it's desirable for a passenger car tire sidewall to flex and a trailer tire sidewall not to flex, but you are correct, they absolutely do recommend running max pressure in trailer tires.


Folks, please, PLEASE recognize this is not the case with passenger car and light truck tires! No manufacturer, not one, recommends running max pressure in a car or truck tire unless you are at max load. Every car has a placard, usually on the drivers side door post, with recommended tire pressures. The number on the side of the tire is NOT the recommended pressure!

Jim, I'm sorry for derailing your thread. You were right, I was wrong. I saw what I wanted to see, not what you wrote.

For my 2 cents, I'm not trying to convince anyone to do anything. I'm just passing along information that I've found that comes from what I believe to be reliable sources, like this one. http://www.trailmastertrailers.com/pdf/ ... safety.pdf

I will point out that tear drops are an exception to most other trailers. The majority of trailers fall into two categories,
Travel trailers, which are made by manufacturers that pick the cheapest tire they can that will support the weight of the trailer, and when loaded by its owners, is probably over the limit of the tire. In this case for a manufacturer to recommend Max tire pressure makes total sense
The other group is cargo trailers of one type or another. They may run empty one trip and full the next, so in this case it makes sense for the tire mfg to recommend max pressure, because you should prepare for the worst case wear.

The TD weight is usually much lighter than the tire max capacity, and the weight of the TD doesn't climb significantly when loaded ( at least with the ones I've seen). So I still believe that there is plenty of room to reduce the air pressure on these tires to conform with the lower load rating. When done properly this should reduce the heat and wear on the tire. No I'm not a tire engineer, and I'm not trying to talk anyone into doing what I do. But that is what I do.
Tom