Tire pressure on motorhome

[Pairajays]

Midniteoy,

What do you mean by mandated? RV manufactures must put on TPM systems as standard equipment?

Jim E

[Elkhartjim]

This thread is becoming a joke. I prefer to do what the tire, wheel, rv manufacturer says do cause most of them hold a lot more than 12 patents. I just don't want to end up a patient.

I had an experience this morning. My toad has a tpms. The light was on indicating low air pressure. I checked an sure enough I had 26 psi in a tire that should be pressured to 32 psi. I drove three miles and the light went out. Just for the heck of it I stopped, checked the air and had 34 psi. Now if I let 2 lbs out to bring it down to the recommended 32 psi then in the morning I would have 24 lbs so then I add 2 lbs, drive three miles and let two lbs out. This would never end. Like I said, this thread has gotten way too crazy for me.

Safe travels at whatever pressure you choose to drive.

[Midniteoyl]

Originally Posted by Pairajays

Midniteoy,

What do you mean by mandated? RV manufactures must put on TPM systems as standard equipment?

Jim E

Sorry.. mandated for cars, SUVs, Trucks and Light Buses as of the 2008 model year, starting with builds after Sep. 1 2007.

FleetMag.com- Article - TPMS Mandate Will Affect all New Car Buyers in 2008

[akadeadeye]

Originally Posted by Craig1959

As someone with 12 patents to his name, I am comfortable arguing contrarian positions. But I will admit that I am disappointed when people blindly follow so called 'safety warnings' without thinking.

I have one question: How can an intelligent person say that it is dangerous to bleed air from a warm tire? Is it going to explode? Are the fumes going to kill you?

Pointing to random manufacturer's warnings does little to help. For example: My F-53 manual says you MUST check lug nut torque on all wheels every time before you drive. Clearly this warning is written by a lawyer. I will certainly question the intellect of anyone who follows this kind of warning to the letter.



You speak like someone without a TPMS. You should get one. Within a few days of driving you will be able to record the information that manufacturers will not normally provide. You will quickly learn what the normal warm temperature relative to the published cold temperature.

Think! Why do manufacturers tell you to NOT bleed warm air? They're afraid that you will bleed down to the published cold temperature and then end up under-inflated when your tires eventually cool down.

When I bleed warm air, I bleed down to the normal warm temperature that I have observed hundreds of times in the past.



Ambient temperature is irrelevant to someone using a TPMS. You simply react to the PSI shown on the TPMS screen. If you haven't started driving, you match the published cold temperature, regardless of ambient outside temperature[. Ambient temperature is the cause for changes in pressure. The TPMS simply reflects the result of temperature changes. That's what you need to care about.

Once you start driving, you then use you TPMS to match the normal observed warm temperature. Simple, accurate and much safer that relying on old-fashioned cold temperature readings.

Someday, manufacturers will publish warm tire data. For now, only TPMS owners will have the ability to drive with this extra level of safety.

I have TPMS and use it only for the purpose of being able to tell if I am losing pressure.

Tell me, do you do this with your personal vehicle (towed vehicle) also. To follow your logic, we should all pull over numerous times per day whether in an RV or passenger vehicle to let air out of our tires. I must say I have never heard of such a thing, nor have I ever heard of anyone else doing this.

You seem to be very sure of yourself and convinced you are right. Be sure you have a "roadside assistance plan" and I wish you safe travels.

Don

[bigdog]

Went for a ride yesterday in the DWs 2010 Ford,which I don't usually drive and while going down the freeway after driving for about 1/2 hour,the low air pressure light came.I pulled over and visually checked all the tires and they looked ok,so I grabbed the pressure gauge and physically checked them all and they were all equal and even pressures.Got back in the car and started it up and the light was out...Just before we got home,it did it again,so I finished getting home and checked each one again and they were ok. It has happened before with her on short trips,she says,but they all went out when she stopped the car.Called the local Ford Stealer where she got the car and he said that it never happens that way,so I called the dealer I get all my work done at and the shop where I get my MH work done and both of them said that this does happen and to take it back to the Ford dealer and have them replace them..
I can just see me going down the freeway sometime with sensors and they tell me that I am getting a flat and pulling over on the shoulder and it didn't happen..NAWW!!

[Pairajays]

Midniteoyl,

I think I have TMPS on my 2004 Ford Explorer. When I turn on the ignition, a little icon, that looks like a tire, flashes on my dash. Then it stops after a couple of seconds. No where in my owners manual does it explain what this is. I assumed it was a TPMS. Have no idea how it works, where the sensors are or how/when to replace the batteries.

JimE

[Midniteoyl]

Is the icon like this?

[Midniteoyl]

Here's some info on '03 and newer Explorers.. or any system, really.

Info On Tire Pressure Monitoring Systems (TPMS) - Ford Explorer Ranger Enthusiasts "Serious Explorations"®

[Triker56]

Originally Posted by Elkhartjim

This thread is becoming a joke. I had 26 psi in a tire that should be pressured to 32 psi. I drove three miles and the light went out. Just for the heck of it I stopped, checked the air and had 34 psi. Now if I let 2 lbs out to bring it down to the recommended 32 psi then in the morning I would have 24 lbs so then I add 2 lbs, drive three miles and let two lbs out. This would never end. Like I said, this thread has gotten way too crazy for me.

You should have drove to a place to put air in the low tire.
If you had checked the pressure in the other 3 tires. They may have been at 37-38 PSI and you could have put 3-4 PSI more in the low one.

One summer when on a trip I had one tire on my cargo trailer show it was low. I drove 30 miles to a Flying J and after fueling up the MH and letting the tires to cool some.
I put the same PSI in the low tire that was showing by TPMS in the other tire.
Next morning after sitting in a campground, both tires showed the same PSI.

Tires will lose or gain 2% PSI for every 10º of temputure change.

[Craig1959]

Originally Posted by akadeadeye

I have TPMS and use it only for the purpose of being able to tell if I am losing pressure.

Tell me, do you do this with your personal vehicle (towed vehicle) also. To follow your logic, we should all pull over numerous times per day whether in an RV or passenger vehicle to let air out of our tires. I must say I have never heard of such a thing, nor have I ever heard of anyone else doing this.

You seem to be very sure of yourself and convinced you are right. Be sure you have a "roadside assistance plan" and I wish you safe travels.

Proper PSI maximizes load carrying capacity across a range of pressures thereby increasing safety and reducing 'mysterious' blowouts. You also get the most comfortable ride possible. I use my TPMS for this purpose in addition to getting low pressure and blowout notification.

Car tire pressures are less of a concern since you are not generally near the maximum carrying capacity of the tire. If you were, you would experience more of the 'mysterious' blowouts that truckers and RV owners complain about. If you used your TPMS more fully you would have more metrics and would convince yourself to monitor your MH PSI more carefully.

Optimum carrying capacity occurs at a single pressure with an associated upper and lower range that provides similar carrying capacity. Outside that range (an inflection point), carrying capacity falls rapidly. The lower (cold) limit is generally published. The optimal PSI and higher limit must normally be calculated or observed. Manufacturers should provide this graph. I suspect their lawyers don't want this information to be shared since uneducated users can potentially misuse it (confirmed by many of the comments related to my original posting). As such, the rest of us suffer.

I never said you need to do these types adjustments on a regular basis - only when you are exceeding recommended ratings. If you don't have a TPMS, you won't know it is happening. If you ignore what you are being told, then a TPMS is not much help (see below).

Personally, I will bleed air to maintain a softer ride - not for some undue concern about safety. Adding air is done more regularly when I expect my warm PSI to be outside the optimal carrying capacity range (as described above). Most such adjustments happen this time of year when ambient temperature swings are large. As I have said before: Your tires don't care about ambient temperature. They care about the results: The change in PSI.

I haven't convinced myself of anything. I understand the topic. Many people and manufacturers (and quite likely the lawyers) are espousing their adherence to 1950's methodologies. They should know better. This will change as proper TPMS usage becomes more common.

Originally Posted by Elkhartjim

This thread is becoming a joke. I prefer to do what the tire, wheel, rv manufacturer says do cause most of them hold a lot more than 12 patents. I just don't want to end up a patient.

I had an experience this morning. My toad has a tpms. The light was on indicating low air pressure. I checked an sure enough I had 26 psi in a tire that should be pressured to 32 psi. I drove three miles and the light went out. Just for the heck of it I stopped, checked the air and had 34 psi. Now if I let 2 lbs out to bring it down to the recommended 32 psi then in the morning I would have 24 lbs so then I add 2 lbs, drive three miles and let two lbs out. This would never end. Like I said, this thread has gotten way too crazy for me.

This thread is fascinating because you can't Google to find the answer.

If I cared to file a patent in this area I would add a strain gauge to each wheel and a speed sensor to the existing PSI and temperature sensors. The integration of these sensors would create a TPMS that is vastly superior to the current state-of-the-art. Most people don't know that speed affects carrying capacity much more than PSI. A system that includes a measure of speed along with weight on the axles will eventually be a major advancement. Given what I have read in this thread, I should probably build such a device. It will probably save a few lives.

When you started driving this morning, your car tires were underinflated. Your car's minimal pressure warning system told you this and you chose to ignore the warning. It sounds like you think the sensors were wrong. They weren't. Until your tires warmed up, they were underinflated. Your tires eventually reached their minimal operating range and your monitoring system confirmed it.

You caused more tread wear than normal but saw no other ill effects. The odds were on your side since your car was likely not near its weight carrying capacity. With a MH you are likely to be close to the maximum carrying capacity and should be more careful.

Many thanks for providing me with such a good examples of how people misuse tire readings.

Now. Rather than just flaming me, try to dispute the facts I have presented. Use Google. Ask an expert. In the end you will discover that this is actually the best tire advice you ever receive - at least in this century.

[allynne]

Craig,

As stated before that is the biggest bunch of nonsense I have ever read even on this site.

Good luck!

Al Sawyer
'05 MADP

[Pairajays]

Midniteoyl,

Yea, that's what my icon looks like. That's a lot of info to understand and follow. My tires have been replaced and rotated several times. Sounds like something should been done to calibrate the system each time. I'm not going to worry about it.

Jim E

[Old Bounder]

What a bunch of garbage....

A great example of "seldom right, but never in doubt"

Set the pressure of your tires, where you want them, COLD, and LEAVE THEM ALONE....

[Midniteoyl]

When you started driving this morning, your car tires were underinflated. Your car's minimal pressure warning system told you this and you chose to ignore the warning. It sounds like you think the sensors were wrong. They weren't. Until your tires warmed up, they were underinflated. Your tires eventually reached their minimal operating range and your monitoring system confirmed it.

Except that the most common TPMS's in use on cars/light trucks usually only tell you if you are >25% out of range.