TPMS: Too much info... how hot is too hot?

[Dakota 1120]

Originally Posted by AlaskaErik

That's an old wives tale. I've never seen tires rated that low, although they probably exist. My Goodyear Endurance tires are speed rated to 87 mph, which is faster than I'll ever pull either of my trailers.

Also run Goodyear Endurance tires and yes, speed rated at 87 MPH. Maxxis are also speed rated about the same.

Interstate speed limit here is 85 MPH but seldom exceed 70 MPH.

[Tireman9]

Originally Posted by AlaskaErik

There seems to be some controversy about the Q rating of those tires. Maxxis, on their web site, labels these tires as high speed. I'll let others debate that one. My Goodyear Endurance tires are officially designated as being speed rated to 87 mph and I've towed my KZ at speeds up 80 mph.

Everyone needs to realize a couple things about "speed Ratings"


1. the load formula for ST tires is based on a MAX operating speed of 65. To run faster you would need to reduce your load and increase inflation.


2. The SAE speed test is designed for "passenger car tires" and is a 30 minute step speed test and tires only need to run 10 minutes at the rated speed without coming apart to "pass".
Also the load is limited to 80% of the tire Maximum load (number on the tire) so you need to consider that if you are running near the "speed Rating" you are probably running at greater load and lower pressure for longer than 10 minutes. Also at the end of the test the tire is considered scrap. Do you consider your tires scrap after 10 minutes of running your max?


The "Speed Rating" is used by tire engineers as a comparison of relative heat resistance.

[Tireman9]

Originally Posted by AlaskaErik

That's an old wives tale. I've never seen tires rated that low, although they probably exist. My Goodyear Endurance tires are speed rated to 87 mph, which is faster than I'll ever pull either of my trailers.

Up untill 2017 ALL ST tires were rated 65 max. Check many RV owner's manuals for older trailers and if they say anything about tire speed they say 65.


The change in 2017 cam about in response to China "dumping" low cost tires with no speed rating in US market so almost overnight almost all ST tires suddenly became speed rated.


read my other posts on Speed rating.


So not an old wives tale. I think you just didn't know about the limit.

[billywilly]

Thanks Tireman.

[LittleBill]

Prior to getting TPMS for my 5er and on my TT, I checked air pressure and didn't worry too much about high air pressure or high temperatures. Then I acquired TPMS for my 4 tires. I set the low/high pressure setting to the recommendation in the manual which I believe was to 10-15 percent above cold pressure. It wasn't long before the TPMS was going off due to high pressure. So I kept bumping it a little bit till it no longer would go off.

One thing I learned along the way was to increase the tire pressure to the reading on the tire, not the 90 psi it came with from the dealer. Then I came to the realization is not to worry about how high the pressure/temperature rises as before I got the TPMS, I never worried about those things. I only worried about not knowing if/when I should have a blow out or loss of air.

Now I will need to watch to see if temps rise to the 158/above mark and then take some action. I have seen my temps rise to 125, to say the least I was concerned. But I am only concerned because the TPMS is telling me what it is. Before I had TPMS, I really never knew how high things were and when I stopped after a couple of hours driving, I would check the hubs to see if maybe the brakes were dragging or anything else that might cause them to be hot.

I guess what I am saying, I am more concerned about losing air pressure that would indicate I'm about to have a flat or have had a blowout, then how high the temps/pressure rises. Just my thoughts right or wrong (which I probably am)

[jimmarako]

Originally Posted by LittleBill

Prior to getting TPMS for my 5er and on my TT, I checked air pressure and didn't worry too much about high air pressure or high temperatures.
Now I will need to watch to see if temps rise to the 158/above mark and then take some action. I have seen my temps rise to 125, to say the least I was concerned. But I am only concerned because the TPMS is telling me what it is. Before I had TPMS, I really never knew how high things were and when I stopped after a couple of hours driving, I would check the hubs to see if maybe the brakes were dragging or anything else that might cause them to be hot.

Yep, exactly why I started the post. TMI!

Jim M.

[Tireman9]

I have said in my blog that I wish they did not include temperature as the extra information is not as important as ensuring you inflate to proper cold inflation and to never run when the tire is under-inflated.


When you read THIS post you will better understand why tires fail. Short term low inflation is what TPMS will warn you about after you have your TPMS properly programed. The long term failure (belt separation) potential can be decreased with proper inflation. It is also important to remember that you can damage the tire structure bu running overloaded or under-inflated or at high speed and importantly remember that damage does not repair itself so damage done last week or month can eventually lead to a failure next month.

[2005gts]

ponder this.... my 2005 FR Lexington GTS 255DS has a label inside one of the cabinets that shows to inflate front tires to 60lbs and rears to 65lbs. this seems to fly in the face of 'conventional wisdom' that says 70 to 80 fronts/rears...

Bill

[Tireman9]

Originally Posted by 2005gts

ponder this.... my 2005 FR Lexington GTS 255DS has a label inside one of the cabinets that shows to inflate front tires to 60lbs and rears to 65lbs. this seems to fly in the face of 'conventional wisdom' that says 70 to 80 fronts/rears...

Bill

Don't know where you came up with "conventional wisdom". There are federal requirements that the inflation on 2005 RV would be sufficient to support the GAWR of that particular RV. If there were different equipment that changed the front or rear GAWR then the inflation also might have changed.
Are there any Class-C RVs out there that have slightly different GAWR such that the load capacity of tires in Dual position at X psi was equal to the rear GAWR while the same inflation in single (front) tires matched the front GAWR?


Also I trust you are not comparing 2017 and newer RV as the RVIA requirement changed such that the inflation needed to provide 110% of the GAWR.


Sometimes "Conventional Wisdom" doesn't keep up with changing regulations and requirements.

[billywilly]

After my last blowout, I requested the tire man replacing it to use the “best “ tire available. He responded that no matter what type tire you run on your rig, if it starts leaking air for whatever reason, it is going to heat up, the casing is going to come apart and eventually self destruct. Made total sense to me. So, traveling with my new tire pressure monitoring system checking pressure and temperature, I should be alerted when conditions change so that I can take action to prevent a blowout and the collateral damage. What more can you ask for? Should I strike a road hazard that causes a tire to blow, that is unavoidable.

[Tireman9]

Originally Posted by billywilly

After my last blowout, I requested the tire man replacing it to use the “best “ tire available. He responded that no matter what type tire you run on your rig, if it starts leaking air for whatever reason, it is going to heat up, the casing is going to come apart and eventually self destruct. Made total sense to me. So, traveling with my new tire pressure monitoring system checking pressure and temperature, I should be alerted when conditions change so that I can take action to prevent a blowout and the collateral damage. What more can you ask for? Should I strike a road hazard that causes a tire to blow, that is unavoidable.

Just be sure you know the MINIMUM cold inflation for your tires and their load and that you properly program your TPMS. Some systems can be fine tuned for your personal RV. You can check my blog for instructions and related information.

[billywilly]

Thank you Tireman9. Appreciate your advice. Duly noted and applied.

[2005gts]

Originally Posted by Tireman9

Don't know where you came up with "conventional wisdom". There are federal requirements that the inflation on 2005 RV would be sufficient to support the GAWR of that particular RV. If there were different equipment that changed the front or rear GAWR then the inflation also might have changed.
Are there any Class-C RVs out there that have slightly different GAWR such that the load capacity of tires in Dual position at X psi was equal to the rear GAWR while the same inflation in single (front) tires matched the front GAWR?


Also I trust you are not comparing 2017 and newer RV as the RVIA requirement changed such that the inflation needed to provide 110% of the GAWR.


Sometimes "Conventional Wisdom" doesn't keep up with changing regulations and requirements.

"conventional wisdom", my words, based on what i read on this forum and elsewhere; people think more is better...

spec sticker says:

front GAWR 4500, rear 9450 for LT225/75R16/D

present tires are LT225/75R16/E

Bill

[Homebrew]

I don’t trust stickers any more.
My 2nd trailer was new and the stickers said I had radials with E rated tires, the tire was not a radial and were D rated.
My 3rd trailer the sticker said I had E rated tires and the PSI was 90 , the tire max cold psi was 80 on the tire.

[mwdilday]

Originally Posted by Chuck_S

Run ST (special trailer) tires at the maximum temperature listed on the sidewall. No need to run them softer, no one is riding inside.

-- Chuck

This confuses me. Why does the vehicle manufacturer put a sticker on the vehicle indicating tire pressures?

[mwdilday]

Originally Posted by Tireman9

Just be sure you know the MINIMUM cold inflation for your tires and their load and that you properly program your TPMS. Some systems can be fine tuned for your personal RV. You can check my blog for instructions and related information.

My TST507 TPMS you enter the cold inflation pressure and it determines the limits itself. I believe it is 5% below, 20% above or something like that. It also detects a blowout and alerts immediately.

[Tireman9]

Originally Posted by Homebrew

I don’t trust stickers any more.
My 2nd trailer was new and the stickers said I had radials with E rated tires, the tire was not a radial and were D rated.
My 3rd trailer the sticker said I had E rated tires and the PSI was 90 , the tire max cold psi was 80 on the tire.

If the trailer was sold as new you should have filed a complaint with NHTSA. At a minimum you would have received new tires since you depended on the certification lable being accurate. To not have tires matcj the lable from the MFG is violation of DOT regulations.

[Tireman9]

Originally Posted by mwdilday

This confuses me. Why does the vehicle manufacturer put a sticker on the vehicle indicating tire pressures?

Required by law. Tire load capacity is established by inflation. Tires MUST be capable of supporting 50% of GAWR per DOT and 45% of GAWR per RVIA so to know the tire load capacity they need to specify the minimum inflation level.

[Homebrew]

Originally Posted by Tireman9

If the trailer was sold as new you should have filed a complaint with NHTSA. At a minimum you would have received new tires since you depended on the certification lable being accurate. To not have tires matcj the lable from the MFG is violation of DOT regulations.

I did file a complaint on my 2nd trailer and received new tires and rims.
This was a battle and very exhausting.
On my 3rd trailer I figured the PSI was a miss print and followed the tire recommendation.

Tireman -many people are trying to figure out the rim PSI when there is only a weight stamped on the inside of the rim. Do you have any advice on how to determine the rim PSI rating ?

[Tireman9]

Originally Posted by Homebrew

I did file a complaint on my 2nd trailer and received new tires and rims.
This was a battle and very exhausting.
On my 3rd trailer I figured the PSI was a miss print and followed the tire recommendation.

Tireman -many people are trying to figure out the rim PSI when there is only a weight stamped on the inside of the rim. Do you have any advice on how to determine the rim PSI rating ?

Complaint with dealer might have been a problem but I would not think so if the complaint was filed with NHTSA as they could order a recall of every rv sold to have tires and stickers inspected and fixed.




For a wheel that is not labeled with psi I would try to contact wheel mfg but you can also look at the cold PSI on the tires that came from the mFG and I think it is reasonable to assume the tire is at least OK for the pressure on the tire + 20%.
Most LR C (50)tires come on same wheels as have LR=D (65 psi) tires.


It may take some digging to find the company that supplied the wheels to FR. You can try and contact TREDIT as they supply many tire/wheel assy already mounted Look for any other marks and numbers on the wheel as that might help TREDIT ID the wheel.