Hot Trailer Tires

[Maggie S.]

This weekend . . . we stoped to feed the kids a snack, about an hour after having left home & had been driving on the freeway. Both my husband and I thought the tires of the trailer felt "too" hot. We continued on and all went well but . . .what could that mean . . . if anything? Is it normal for the trailer tires to be hot or am I just a "Nervous" Newbie?

[Doug Mager]

Not THE expert to be askin, but this might just be normal. Did you compare temps with your tow vehicle? Tires usually heat up while in use and WILL expand and possibly blow out IF they were over inflated to start with. The tires may have been overinflated OR undewrinflated, either issue may cause them to be hot, but one must consider also the overall wheel/tire size. Smaller ones make more revolutions per mile than larger diameter ones. I think I'd be more concerned about feeling the WHEEL surface especially closer to the center (hub) portion. Too much heat there can indicate a faulty wheel bearing which could be more trouble than just a simple flat (blown out tire)

[Roger H]

Doug hit on the key... it's the relative temperature of a tire in relation to the other tires on that side. Sunlight can make a huge difference in the sidewall temperatures of all of the tires on one side of the rig, for example. And your tow vehicle tires should be roughly the same temp as your trailer tires under similar circumstances.

Roger

[Maggie S.]

And your tow vehicle tires should be roughly the same temp as your trailer tires under similar circumstances.

Roger

Both of the trailers tires were hot on the side walls and the tow vehicles tires were, maybe a little warm, but no where near as hot. We didn't touch the rims or wheel surface.

The tow vehicles tires are much bigger than the trailers tires.

Maggie

[Pete Dumbleton]

I make it a habit to either hand-check (if it's too hot to hold your hand on it, it's too hot!) or infra-red thermometer check both the truck and trailer tires and hubs often so I get a feel for what normal is under a number of weather and road conditions. What I am looking for is not a particular temperature, but a tire or hub that is different from all the others (on that side as Roger H pointed out because sunshine can make a big difference). At the same time, as I walk around checking, I am looking for other stuf wrong, like coupler, safety chains, etc.

[Darwin Maring]

Pete is right on. I do the same thing by using a non contact thermometer.
Look at this site for one:
http://search.harborfreight.com/cpisearch/...r&Submit=Go

I always check the hubs because if you have one getting hot, that is quite serious. Then I check the tires. I have a log where I write the readings so I will be able to spot a trend (A Hub going bad).

On the tires: I installed valve caps that have a preset preasure reading. They show Green when the preasure is where it belongs and show RED should I loose 2 pounds of preasure.

There are 2 kinds, Ones that are preset at a preasure and will say so on the cap such as 45 and the other kind are the ones that you fill the tire then put the cap on and they take the reading and will turn red should you loose 2lbs of preasure. I have the labeled ones on the egg and the other kind on the truck. You can find them at www.jcw.com

[Byron Kinnaman]

Pete is right on. I do the same thing by using a non contact thermometer.
Look at this site for one:
http://search.harborfreight.com/cpisearch/...r&Submit=Go

I always check the hubs because if you have one getting hot, that is quite serious. Then I check the tires. I have a log where I write the readings so I will be able to spot a trend (A Hub going bad).

On the tires: I installed valve caps that have a preset preasure reading. They show Green when the preasure is where it belongs and show RED should I loose 2 pounds of preasure.

There are 2 kinds, Ones that are preset at a preasure and will say so on the cap such as 45 and the other kind are the ones that you fill the tire then put the cap on and they take the reading and will turn red should you loose 2lbs of preasure. I have the labeled ones on the egg and the other kind on the truck. You can find them at www.jcw.com

I'm going to add two ya-buts here.

1. IR thermometers are air temperature dependent. That is with the same object temperature and different air temperatures you'll get different object readings. So be aware of this limitation.

2. Air pressure devices on the ends of valve stems can be prone to leaks. The Schrader valve in the stem is designed to seal tighter the higher the pressure. When you put something on the end of the valve stem you defeat that design. The Schrader valve is forced open. The seal, to keep the air in, is now dependent on the outer rim of the valve stem and the device. Any seal at that point is subject to leaks. The valve stem is not manufactured for a seal at that location, therefore the rim might not be smooth and even. Air pressure working on the end of the valve stem seal attempts to open the seal instead of tighten it like the Schrader valve. The end result is that you they will tell you when a tire has low tire pressure and also might be the cause of the low tire pressure.

[Maggie S.]

Hmmm . . . now I'm getting some ideas on what to buy my husband for Xmas! He can go around zaping the tires. Sounds very star trek & didn't know those things even existed -- so thanks for that info.

The whole hub issue sounds like something to be concerned about & we are planning our first big trip next July -- up to the "Gathering", over hill and dale.

Can the hub be found to be going bad when we re-pack the bearings, something we haven't done yet but will be doing soon? We were going to attempt to do it ourselves. The re-packing seems like something the husband could do.
I guess the question is, would a bad ball bearing be something he/we'd notice?

Maggie.

[Brian B-P]

Yes, bearing condition can be assessed in the repacking process, and most people can do that... if they're willing to learn, try, and get a little greasy.

The bearings are rollers, not balls, but I know what you mean, Maggie...

It's amazing to me how badly damaged a tapered roller bearing can get and still work okay on a vehicle... you may not notice until you jack it up to take the load off the wheel, and find the wheel and hub slopping loosely around on the spindle!

[Darwin Maring]

It appears that they have made some major design improvements in the valve cap and tire pressure reading devices. Should the tire pressure go down for any reason, the spring on the inside of the device will push the indicator to the red position making it quite visible.

The designs in tire inflation and control have gotten so good that the Military Hummer for instance is able to change tire pressures while under way. A very neat trick on a moving vehicle.

http://www.jcwhitney.com/autoparts/Product...ewflag-1#review

The INFRARED THERMOMETER reads the spot the laser is targeting and the slightest movement in any direction will reflect the different temps being read. The farther away from the object, the bigger spot the thermo is reading. You get the best reading up close and you do not have to touch the object and the reading is instant.

The site below will take you to JCW and will give you an idea just how far away from an object you can be to still get an accurate reading. The one at www.harborfreight.com is less expensive with less bells and whistles and works just fine for reading temps on the hub and tires.

http://www.jcwhitney.com/autoparts/Product...ewflag-1#review

Maggie: Before he does the repack he should get a mechanic book and study how to do it. It will show him how to clean and repack. It will tell him what not to do and the proper way to pack the grease back in the bearings. It will tell him what to look for to make sure he has good bearings and the type of grease and the grease seal to replace with a new one. Look at www.jcw.com for a book. They also have catalogs for RV's, Trucks, and all sorts of vehicle stuff.

[Byron Kinnaman]

It appears that they have made some major design improvements in the valve cap and tire pressure reading devices. Should the tire pressure go down for any reason, the spring on the inside of the device will push the indicator to the red position making it quite visible.

The designs in tire inflation and control have gotten so good that the Military Hummer for instance is able to change tire pressures while under way. A very neat trick on a moving vehicle.

Take a good look at the end of the valve stem. That surface is where the seal is made. Every time you put a gauge or fill the tire you risk nicking that surface. Every time you remove the device you take a chance on getting dirt and other stuff in device seal and/or on the rim. A human hair across that sealing surface will cause a leak.

I don't think any military vehicle is relying on the end of the valve stem to seal air in the tire.

The INFRARED THERMOMETER reads the spot the laser is targeting and the slightest movement in any direction will reflect the different temps being read. The farther away from the object, the bigger spot the thermo is reading. You get the best reading up close and you do not have to touch the object and the reading is instant.

The site below will take you to JCW and will give you an idea just how far away from an object you can be to still get an accurate reading. The one at www.harborfreight.com is less expensive with less bells and whistles and works just fine for reading temps on the hub and tires.

IR is light. The system is an optical system. The laser targeting only points to somewhere close to the middle of the spot. The reading is an average of all the temperatures (IR energy) inside the spot. The farther away the larger the spot averaged. Depending on the optics the close reading maybe even farther off. Remember it's optics, get real close with your camera and see how distorted the image is. The temperature the device is operating in makes a big difference in the temperature reading. It follows the "black body" curve. How do I know all this and more? For the last 10 years I've been designing and fine tuning an IR thermometer designed for vehicle use. The one I've been working on mounts on a truck mirror and measures the road temperature along with the air temperature. Read about RoadWatch here.

[Brian B-P]

The Central Tire Inflation System used on some HMMWV and other military vehicles (and optionally the now-defunct civilian Hummer H1 version) certainly does work... and it indeed does not just attach to the valve stem. The really impressive part to me is that it connects an air line on the truck to the tire through a rotating coupling, which still manages to hold air. Of course, if it leaks a bit it can just pump in replacement air - not an option for devices stuck on the valve stem ends.

[BOBSMITH]

Here's another thing. If a tire is under-inflated, it can cause the air inside to really heat up and expand. In some cases this can even result in a sudden rupture.

[Steve Hilby]

Here's another thing. If a tire is under-inflated, it can cause the air inside to really heat up and expand. In some cases this can even result in a sudden rupture.

It's not so much the air expanding and causing a rupture. What happens is that because of the underinflation the sidewall flexes way more than it's designed to, and eventually the reinforcing cords in the sidewall rubber break, and then the tire deflates. Rapidly.

[Steve L.]

Generally, what happens is that as the tire overheats the rubber actually begins to revert (in a very loose sense it "melts") and it looses it's adhesion (ply to ply and even cord material to the rubber it's embedded into). Then inflation and centripetal force causes the tire to come apart.

Confusing this somewhat is that if the tire runs flat the wheel rim can cut the body ply material. Broken cords are usually a secondary effect not a cause.

I'm not saying that broken cords can't cause a failure. I'm just saying that overheating in the fashion described doesn't fail cords.

[Darwin Maring]

Steve, You really struck a cord with that post.

[Steve L.]

Steve, You really struck a cord with that post.

Groan!

[Alf S.]

Groan!

Hi: According to my thinking a good visual/sensual inspection along with a tire pressure gauge and proper inflation rates makes good trailering sense. While changing over from cracked bias ply to new radial trailer tires was a good time to do a bearing repack and the $20.00 my R.V. dealer charged+ $5.00 for new seals was a bargain. He also used a very neat little device(Grease cup) to drop the bearings into and force the grease through the bearings. Something I do not have... now all I have to do is keep track of towed miles and do a repack every 5000KM. thats Canadian EH!!!
Alf S. North shore of Lake Erie

[John Perry]

Hi Maggie,
As usuall Alf has some good advice.
Get a good tire gauge, make sure your tire are inflated to the proper pressure and HAVE your wheel bearings packed by a mechanic.
Problems never happen close to home. If you do not pack the bearings properly You will probably be 7 hours for home with cranky kids when the wheel beraings go bad. It is not only inconvenient but it can be a very expensive proposition. You could possibly damage a spindle and then you would probably have to replace the entire axel.
The 20 or 30 dollars you spend is cheap insurance.
Get a good tire guage, make sure your tires are in good shape and properly inflated, have your bearings packed by a pro and then the next thing you should do is RELAX and have fun enjoying being out with your family.

John

[Maggie S.]

Under inflated?

Sorry if this sounds really dumb . . .

So, hubby went out and looked at the tires. It says max tire pressure is 50 psi cold. The right tire was 22 and the left was 26 cold. Would that have been under inflated? It says nothing about what is too low.

What is a good tire pressure to have them inflated to if max is 50? Should they be at 50? 40? What is the proper pressure?

I just bought a digital tire gauge at Costco.


I priced a repack and it was $110. Yikes, I like your price better John (20-30)! But yes, I think I'd rather have it done.