Hot Tires

[dmac]

All the literature that I have read over the years says to check/set tire pressures when cold... before driving more than a couple miles. Per the 2003 Airstream Safari/Bambi owners manual:

"Check the pressure in your tires, including your spare, at least monthly when the tires are cool (after the vehicle has stopped three hours and then driven less than one mile.) Do not reduce pressure when tires are hot. Use a tire gauge to check pressure and maintain it at the recommended level."

and

"To get the maximum performance from your tires check the air pressure often, but only when the tires are cool. Never bleed out air immediately after driving."

I agree that you should use the pressure recommended by the vehicle manufacturer. In the case of my Airstream the trailer manual says to inflate to 65 psi, and the sidewall of the tires says max pressure 65 psi - the same.

[bryanl]

"One way to make sure you have the proper pressure is to check them before you start on a ride on a day without any extreme weather. Then check the pressure twenty miles or so down the road. If the pressure in the tire has gone up more than ten percent or so, you didn't get enough air into them in the first place (heat makes the pressure rise more than it should). So add air if the pressure after twenty miles or so goes up more than ten percent. If you have an infra-red non contact thermometer (Radio Shack or some tool places for under $50) you can check tire temperature as another indicator of proper pressure. The tire temperature shouldn't get more than thirty degrees or so above ambient air temperature."
http://sierranevadaairstreams.org/ow...ing/tires.html

[overlander63]

Originally Posted by TomW

I do not believe that is correct. Tire pressure, as set to the pressure indicated on the sidewall, should be gauged before the tire has heated up.

I would welcome other opinions.

Tom

Tire pressure should be checked and adjusted when the tires are COLD. A tire is considered cold when it has sat overnight and has been driven less than a mile since it has sat overnight. Checking/ adjusting pressures when tires are warm or hot will result in an underinflated condition, cause more heat to be generated in the sidewall from flexing, and will cause more "roll" (sway) in the trailer or tow vehicle.
Also, if a tire is marked with a maximum inflation pressure of 65 psi, and the wheel is marked with a maximum inflation of 45 psi, do not inflate the tire over 45 psi cold.
The tires on my van have a max inflation of 44 psi, but the wheels say 35, I run 35 psi in my tires. I don't want the wheel coming apart.

[basecamp]

Tire manufacturer knows best. I now have D rated tires on my 96 Excella, they came with C rated back then and yes I believe the side of my trailer says 50lbs. I run between 60 and 65 cold on the D rated Marathons, my dishes are still intact, at least the paper ones.

[Cracker]

IMHO, if I inflated the rear duals on my truck to the 80 psi indicated on the door sticker I might just as well fill them with concrete. Weigh first, and inflate accordingly - but per Goodyear's recommendations for my particular tires, I don't run with less than 45 psi in the tires under any load. Accordingly, I inflate the duals to 55 psi and it makes a world of difference in the ride. At that pressure, and when running unloaded, the rear axle capacity still has a safety factor in excess of 100%. I inflate the duals to 60 psi for my fully loaded condition - and I generally keep the front tires at 65 psi (vs GM's 70 psi) all the time. If you're towing a maximum pin weight 5th-wheel, GM's 80 psi is probably about right for the duals. My tread wear, at 31,000 miles is just about perfect for the duals. I wish I could say the same for the front tires on the truck, however they're experiencing a tread wear pattern that I understand is problematic with aggressive tread designs. The individual knobs of the tread, somewhat uniformly across the tire, have this "sloped" face, with the slope going down towards the front of the truck when looking at the top of the tire. The left and right tire both display the same wear. I have plenty of tread left, but I'm debating on whether to switch the front tires from side to side before my next long trip? I've rotated all 7 tires twice - so far - but, at this point, I'll no longer rotate the entire set. Even though the truck is 4wd, my next set of tires will be more along the line of a less aggressive tread.

[gotair]

"LEGAL DISCLAIMER" Any statements made previously re: tire maintenance should be
considered conversation. Not endorsed by any tire manufactures or trailer manufactures. You should always refer to your owners manuel.
GEE WHIZ!! We sure got off the topic of hot tires!

[Cracker]

gotair2:

I went back and inserted a "IMHO" in front of my preceding entry to comply with your 'LEGAL DISCLAIMER" comment (HaHa!) but if the day comes when we can be taken to task for discussing our hobbies with other enthusiasts, and telling about how we have resolved issues we've faced, it'll be a sad day indeed! I would never apply informaton I've gained through Forum topics, without first making a decision that to do so makes good sense to me personally. That said, if the information I relied upon proves to be in error, I have no one to blame but myself. I certainly hope we haven't abandoned all personal responsibility for what we do!

On the other hand, if a particular entity's (i.e. - Goodyear, Airstream, etc.) l representative provides information to me, while specifically acknowleging that he represents that entity, I might be inclined to raise pure bloody h--- if the use of that information results in any loss or suffering on my part! That's generally why so many manufacturers or companies refuse to answer questions we might propose to them - and why lawyers make so much money defending them when they do!

Your comment brought up an interesting side topic that should probably be pursued in another thread. I apologize for my departure from the current thread topic.

[john hd]

yeah what he said.....

my point on this is, instead of just inflating tires to carry maximum load why not follow the vehicle manufacturers reccomended specs?

after all, they have all those engineers that figure these things out for us who are not.

unless of course, you work for ford and like underinflated firestones to make the ride nice and cushy for soccer moms!

back to the original point of the thread, warm tires on the front axle. trailer too low in the nose? the obvious conclusion is that one axle is carrying the majority of the trailers weight.

john

[gotair]

assuming>>>> the tires are ok how about this, back it up on a block of wood and spin the hot tires do the brakes drag a little more on the front axel? or can you move the wheel back and forth maybe the bearings are loose... or tight...sorry... last post on the subject .... I think..... but remember ... always refer to the manual ... anything I may or may not say has not been endorsed by any trailer co.. or tire co... or pretty much anyone else... he he ...

[dmac]

Thanks for all the opinions. I was surprised at the amount of temperature difference between the front and rear tires given the slightly nose low condition of the trailer. An inch or two at the hitch must only be a fraction of an inch back at the axles - but it really makes a difference in the load between tires!

I will raise the hitch a notch and see if that levels the trailer, then check the tire temps on my next tow. I may not get to try it until Memorial Day due to work and kid obligations.

[gotair]

Originally Posted by Cracker

gotair2:

Your comment brought up an interesting side topic that should probably be pursued in another thread. I apologize for my departure from the current thread topic.

Mr. Cracker , I also apologize... your post poped up befor I hit the key to send mine.... I was not refering to you... I was refering to any thing in my posts that others might dissagree with...my situation is different in that my wheel says max 45 and tires say max 55 so I defer to the wheel as a max pressure and due to the poor condition of the axle and shocks... combined with the underinflation of the tires (when cold !! ) when the pressures rise to high I will air them down to keep them within the max levels of the rims this is not something that I would recommend anyone else try.. I am working or correcting these issues now getting a new axle and shocks and maybe rims and tires as well... these things take time ...as my pockets are not that deep.. I will promiss not to air down my tires while anyone is looking ...next time one of those NASCAR pit crews airs down a tire I will think of this thread ..

[Anon]

Interesting topic.
I went to check the difference in tire temps on mine, front to back.
Then I realized I only had a single axle trailer!

[sovereignrwe]

One risk of following the manufacturer's recommended tire pressure is that the "recommendation" is based on the original tire line (brand and size) purchased for the trailer by the manufacturer.

As many threads here have covered over and over, many folks are going to Marithons on vintage trailers. Even those who haven't switched to Marithons can not rely on your trailer's recommendations since you can't buy the same 7.00xr15 as came on the trailer when it rolled out of the factory. The static recommendation in your trailer's documentation (in our case in the 70's) is based on engineering and materials for very different conditions (Marithons today vs. 7.00xR15s then, or Goodyear 7.00xR15 then vs. Yokohama 7.00xR15s now).

Being an owner of a Vintage Sovereign, I will also NOT look at what is being recommended for tires coming off the line today on new Sovereigns. This is also a poor recommendation as today's trailers are significantly heavier than mine, making any recommendation invalid.

All of these scenarios provide a good guide for tire pressures, but can not be relied upon for "the perfect" answer.

[overlander63]

Originally Posted by gotair2

my situation is different in that my wheel says max 45 and tires say max 55 so I defer to the wheel as a max pressure and due to the poor condition of the axle and shocks... when the pressures rise to high I will air them down to keep them within the max levels of the rims this is not something that I would recommend anyone else try..

After you put "cold" air in a tire, "NEVER" take air out of a "hot" tire. Those pressures are listed as cold inflation pressure, with engineers and designers have spent years calculating temperature-based inflation pressure increase, and have designed their tires and wheels accordingly. If you deflate the tires when they are hot to the cold inflation pressure, when they cool off again they will most likely be seriously underinflated. Instead of having 45psi, you may wind up with 38 psi, or less, depending on how hot your tires were when you adjusted the pressure, and how cold the tires are in the morning. Then, if you don't fill them up again, you will generate excess sidewall flexing, and much more heat in the tire, with increased risk of tire failure.
This is part of the issue with the Ford Explorer, Ford took a 5000 pound truck, and underinflated the tires, with predictable (at least in hindsight) results.

[thenewkid64]

One other thing to note is that all max inflation pressures on a tire are for maximum load. If the tire is not at maximum load then the inflation can be adjusted accordingly.

now for the $124.00 question. Do you KNOW what each axle/wheel of your trailer or MH weighs. If you know the exact weight, you would be able to adjust the cold pressure in each tire to the exact level that is needed for the load that tire is carrying.

OK, That is a bit much, but still I would be willing to bet that most of you do not know that one side of your trailer weighs more than the other.

Not just on the slide out models. All of them. How much changes from model to model. technically you should be running different pressures side to side if the variance is large enough.

Point is weigh it, and then using the tire manufacturers inflation chart for the weight set the pressure. If the cold pressure will exceed the maximum rim pressure then you need to go shopping. A rim failure caused by over-inflation can be catastrophic (read loss of trailer, tow vehicle, or more). As mentioned by others, the book is a starting point, but tire technology has changed in the last 30-40 years so old references can be obsolete.

Of course this is my opinion and you are free to do what ever you like

[Anon]

3.14 x r x r = C
Simple formula to tell how round yer tires are!

[overlander63]

Originally Posted by thenewkid64

OK, That is a bit much, but still I would be willing to bet that most of you do not know that one side of your trailer weighs more than the other.

Not just on the slide out models. All of them. How much changes from model to model. technically you should be running different pressures side to side if the variance is large enough.

My trailer weighs just under 350 pounds more on the curbside, give or take, depending on how much beer is in the fridge.
Fridge, awning, range, microwave, and grey tank all on the curb side.

[nickcrowhurst]

Originally Posted by pattersontoo

3.14 x r x r = C
Simple formula to tell how round yer tires are!

Oh no, even that's changed, has it? It used to be 2 x 3.14 x r = C (circumference), where 3.14 is an approximation for pi, and r is the radius, when I was at school. Your formula used to be for the area. I blame Einstein and his General Theory of Relativity. Is nothing sacred?? Nick.

[Anon]

Originally Posted by nickcrowhurst

Oh no, even that's changed, has it? It used to be 2 x 3.14 x r = C (circumference), where 3.14 is an approximation for pi, and r is the radius, when I was at school. Your formula used to be for the area. I blame Einstein and his General Theory of Relativity. Is nothing sacred?? Nick.

Crap.
No wonder why my degrees are in Electronics Engineering and Industrial Atuomation!
I suck at geometry!
Hit me with trig though and I will knock yer socks off!
Mechanical engineering is just a method for moving what I program!

[loudruff]

Circumference of Circle = PI x diameter = 2 PI x radius
where PI = PI = 3.141592...

http://www.math.com/tables/geometry/circles.htm

Good luck,
Larry