Tires for 5th wheel

[Tireman9]

Originally Posted by andy29847

tireman9 wrote:

My ST load range tires rated at 3500#s inflated to 80#s were blowing up.

Changed to LT load range G tires rated at 3250#s inflated to 95 pounds (105 is max) and they have been trouble free (12,000 miles).

The LT tire is rated lower because of all the different intended uses (steer, drive, trailer) have to be considered. The actual capacity, if tested for use for trailers only would be north of 4000#s.

Air holds the weight. Tires hold the air.

FWIW, I settled on 95 pounds (70 degrees) because of the way temperature affects tire pressure. My TPMS shows stable temps only a few degrees above ambient temps.

Youse guys changing to tires that can be inflated to pressures above 80 pounds may need to change your valve stems. My trailer wheels were rated for 110 psi but, the wheels came with 80 psi valve stems.

Thanks for clarification. I'm not surprised that different tires have different load capacities.

Your conjecture that your LT tires could be rated to carry 4,000# is interesting. Could you share any of your test data that supports your opinion? Your correct observation that it is the air that carries the load doesn't seem to support your suggestion that simply restricting the LT tire to trailer only application would somehow increase it's load capacity. If that were true then your statement that it is the air that supports the load no longer seems to apply.

I do note that the all steel commercial tires from Sailun come in both LT235/85R16 LRG and ST235/85R16 LRG with the LT restricted to "Trailer Application Only" but the LT is still rated to a lower max load of 3650 while the ST is rated for 4080 Both at the same inflation of 110. So here we ahve a tire company that has actually tested tires. Both restricted to trailer application and the LT is still not rated with higher load capacity. What is it you know that the tire companies don't?

[Big-Foot]

Not to derail the subject - but to post an observation.

One of the best things to use for insulation is air. Better still would be vacuum, but that won't work for our purposes.
I have the TM 510RV TPMS from Truck Systems Technologies. The transmitters screw onto the end of my steel valve stems. Those valve stems are mounted on rubber bushings to the steel wheels.
Now, I have to think that the only temperature measurement possibility left would be the temperature of the air.
Given the laws of physics, I frankly don't think that the air temperature is an accurate indicator as to the actual temperature of the tire itself.

I am now retired from active wheel to wheel competition, but back when I was racing, we took tire temps with a digital probe that we would push into the tread face of the tires in four places across the face.
The tire manufactures all told us that tires are formulated to yield their best traction between 180-220 degrees F. Granted, these were racing tires and not street / highway tires.

My point is that I believe that the temps we are getting from our TPMS are not truly accurate, although they can show trends which would be important information.



Regards - Randy & Dar
2015 F350 CC-DRW-409 Diesel / 2008 Rage'n Stryker 4005 Toy Hauler / 2014 Arctic Cat Wildcat Trail-XT
Sent from my iPad using iRV2 - RV Forum

[andy29847]

Your correct observation that it is the air that carries the load doesn't seem to support your suggestion that simply restricting the LT tire to trailer only application would somehow increase it's load capacity. If that were true then your statement that it is the air that supports the load no longer seems to apply.

I don't understand what you are saying. However, commen sense tells me that 90-105 psi will support more weight that 80 psi. The only question is will the tire hold the air. IMHO, it has been proven that they will. Throw in the thicker sidewalls and deeper tread of the LT, and the ST/LT argument is settled for me. I believe that trailer manafacturers use ST tires for cost reasons. Not because they give good service.

I do note that the all steel commercial tires from Sailun come in both LT235/85R16 LRG and ST235/85R16 LRG with the LT restricted to "Trailer Application Only" but the LT is still rated to a lower max load of 3650 while the ST is rated for 4080 Both at the same inflation of 110. So here we ahve a tire company that has actually tested tires. Both restricted to trailer application and the LT is still not rated with higher load capacity. What is it you know that the tire companies don't?

You just made my argument. The same tire marked trailer only is rated for 4080. Thanks, I didn't know about that example.

[Tireman9]

Originally Posted by Big-Foot

Not to derail the subject - but to post an observation.

One of the best things to use for insulation is air. Better still would be vacuum, but that won't work for our purposes.
I have the TM 510RV TPMS from Truck Systems Technologies. The transmitters screw onto the end of my steel valve stems. Those valve stems are mounted on rubber bushings to the steel wheels.
Now, I have to think that the only temperature measurement possibility left would be the temperature of the air.
Given the laws of physics, I frankly don't think that the air temperature is an accurate indicator as to the actual temperature of the tire itself.

I am now retired from active wheel to wheel competition, but back when I was racing, we took tire temps with a digital probe that we would push into the tread face of the tires in four places across the face.
The tire manufactures all told us that tires are formulated to yield their best traction between 180-220 degrees F. Granted, these were racing tires and not street / highway tires.

My point is that I believe that the temps we are getting from our TPMS are not truly accurate, although they can show trends which would be important information.



Regards - Randy & Dar
2015 F350 CC-DRW-409 Diesel / 2008 Rage'n Stryker 4005 Toy Hauler / 2014 Arctic Cat Wildcat Trail-XT
Sent from my iPad using iRV2 - RV Forum

You are correct that the external sensor TPM temperature readings do not reflect the Contained Air Temperature (CAT) of the tire. I have run direct comparisons with internal vs external sensors and find 10 to 20+ degrees difference.

So using TPM temperature readings are really only good for approximate relative temperature comparisons and you need a lot of experience to know when some temperature change is meaningful or when it is due to some outside influence.

PS I once was one of the guys with the temperature probe back in 70's & 80's.

[Tireman9]

Originally Posted by andy29847

I don't understand what you are saying. However, commen sense tells me that 90-105 psi will support more weight that 80 psi. The only question is will the tire hold the air. IMHO, it has been proven that they will. Throw in the thicker sidewalls and deeper tread of the LT, and the ST/LT argument is settled for me. I believe that trailer manafacturers use ST tires for cost reasons. Not because they give good service.
You just made my argument. The same tire marked trailer only is rated for 4080. Thanks, I didn't know about that example.

Andy we seem to have a failure to communicate.
A Load Range E tire (80 psi) is not capable of passing Federal Safety regulation tests for a LR-G (110 psi) application so despite your opinion that "the tire will hold the air" that opinion is not supported by facts or data other than an observation on your part that your tires haven't failed yet.

If the Sailun ST is the same as the LT and both are for trailer only application why would the company have a lower load capability for the LT than the ST if your idea was correct?

[Big-Foot]

Originally Posted by Tireman9

You are correct that the external sensor TPM temperature readings do not reflect the Contained Air Temperature (CAT) of the tire. I have run direct comparisons with internal vs external sensors and find 10 to 20+ degrees difference.

So using TPM temperature readings are really only good for approximate relative temperature comparisons and you need a lot of experience to know when some temperature change is meaningful or when it is due to some outside influence.

PS I once was one of the guys with the temperature probe back in 70's & 80's.

I still have my TIF Tire temp probes as well as my Brake temp probes and will check the delta between the TPMS temp (air) and actual sub-surface temp of the rubber on my truck when I get a chance.. I'll post my findings here.

I have compared the surface temp from Laser Temp Gun and the sub-surface temps and found a 15-20 degree difference with the surface temps being cooler. However, we attributed much of that from the cooling of the air on the tire as the car was brought into the pits.



Regards - Randy & Dar
2015 F350 CC-DRW-409 Diesel / 2008 Rage'n Stryker 4005 Toy Hauler / 2014 Arctic Cat Wildcat Trail-XT
Sent from my iPad using iRV2 - RV Forum

[Boogie_]

Been trying to follow all the tire threads closely.
Thanks for all the good info.

My rig (31' / 5'er) shows a GVWR of 11,900.
I'm on my second set of Chinese may-pops on 15", 6 hole wheels.
So far I've been lucky with no damage to the camper after several blowouts.


I'm looking around locally as well as on-line for either heavy duty 15" tires or upgrading to 16" wheels.
It will be about 2 months before our next trip so I have a little time to shop around.
I don't have the budget for $2 grand worth of wheels & tires.

From what I've been reading here and tire reviews elsewhere, seems that just going to 16" wheels has solved the problem for most with a rig like mine.
The 16" E Load tires are 750-ish lbs over what the same 15" E tire will carry. So the tires I've been using where marginal at best.
Am I asking for more of the same trouble going with a Chinese ST 16" tire? even though they're rated at 3500 lbs?

And what about this type of tire?
Seems heavy duty enough(?) and I could stay with my 1" wheels.
New 15 inch St 7 00 15 ST7 00 15 Trailer Tire s 12 PR 12 Ply 7 00 700 15 Load F | eBay

Thanks for any help.
B

[justafordguy]

The tire in your link may be a good choice but some of the info seems a little off. It says 12 ply rating (LR F) but also says it's a load range G tire. Also it says it needs a 9 1/2" wide wheel which seems odd for a 7.00 series tire. You may want to call them and get the facts straight. You will also need to check your wheels and see what the max PSI rating is because if the tire is LR G it will probably take 110psi.

[C130]

This topic will never be resolved or agreed upon. My question is how many on here have had blowouts with LT tires? I know every tire has blowouts but I'd be interested in a poll with the ST vs. LT comparison. DOT approval or any government certification is a joke if that's the standard.

[andy29847]

tireman9 wrote:

If the Sailun ST is the same as the LT and both are for trailer only application why would the company have a lower load capability for the LT than the ST if your idea was correct?

Because the LT tire has to be rated for steer or drive positions..

[JIMNLIN]

My rig (31' / 5'er) shows a GVWR of 11,900.
I'm on my second set of Chinese may-pops on 15", 6 hole wheels.
So far I've been lucky with no damage to the camper after several blowouts.

My current 11200 lb wheel trailer came with 6 lug 5200 lb axles and ST225/75-15 D at 2540 lbs. I don't use ST tires so I sold them on CL.
Dropped by my local equipment trailer mfg and bought four 16" 6 lug trailer wheels.
I dropped the wheels off at my Goodyear truck tire dealer and had him mount BFG Commercial LT215/85-16 E load range at 2680 lb capacity. Ran the first set for over 55k miles and now at 48k on the second set with zero issues.
The trailer has 2200-2300 lb of hitch weight = 8900-9000 lbs on the axles or 2250 lb per tire.
The trailer still has a 15" ST as a spare (its never rolled on the road).

Your problem isn't the need of more capacity but a need for quality LT tires.

I'm not a fan of over tiring a trailer. I've towed trailers for a living and found out the hard way the folly of too much tire for the trailer service such as a 110 psi/3750 lb tires on a trailer that came with 15" 2540 lb rated tires. With only 2300-2500 lb on the axles a 3750 lb 110 psi tire will beat on the trailer unnecessarily.
There is no benefit of running a 110 psi tire on a trailer at 80 psi. The E at max pressure will run cooler or at least that was my experience.

[Tireman9]

Originally Posted by Boogie_

Been trying to follow all the tire threads closely.
Thanks for all the good info.

My rig (31' / 5'er) shows a GVWR of 11,900.
I'm on my second set of Chinese may-pops on 15", 6 hole wheels.
So far I've been lucky with no damage to the camper after several blowouts.


I'm looking around locally as well as on-line for either heavy duty 15" tires or upgrading to 16" wheels.
It will be about 2 months before our next trip so I have a little time to shop around.
I don't have the budget for $2 grand worth of wheels & tires.

From what I've been reading here and tire reviews elsewhere, seems that just going to 16" wheels has solved the problem for most with a rig like mine.
The 16" E Load tires are 750-ish lbs over what the same 15" E tire will carry. So the tires I've been using where marginal at best.
Am I asking for more of the same trouble going with a Chinese ST 16" tire? even though they're rated at 3500 lbs?

And what about this type of tire?
Seems heavy duty enough(?) and I could stay with my 1" wheels.
New 15 inch St 7 00 15 ST7 00 15 Trailer Tire s 12 PR 12 Ply 7 00 700 15 Load F | eBay

Thanks for any help.
B

If contemplating a change in size and or type tire you might want to read my two part blog (see my signature ) post "Can I change from ST to LT tires on my Trailer or 5ver?" starting June 24 2014.

Going from 15" to 16" will give you many options including tires from one of the 3 major tire companies rather than "may-pops" from Billy-Jo-Bob's cheap tire and bate shop emporium.

[timetogo]

Originally Posted by Boogie_

And what about this type of tire?
Seems heavy duty enough(?) and I could stay with my 1" wheels.
New 15 inch St 7 00 15 ST7 00 15 Trailer Tire s 12 PR 12 Ply 7 00 700 15 Load F | eBay

Thanks for any help.
B

Did you notice this?

Recommended Rim Widths: 9 1/2 inches wide

[Boogie_]

Thanks Roger.
Lots of good info.
Looks like I will have plenty of reading material for the next few weeks.
I'm in the auto business (own auto parts store, body shop, auto sales) so the lingo isn't that foreign to me.

Definitely moving up to 16" wheels, then pick one of the recommended LT tires that my budget allows.
I have a goose-neck car hauler that has the same size wheels as my camper. The car hauler is a much lighter load, plus very little risk of damage to the trailer from a blow out (compared to the camper).
I'll save the 15" tires I recently bought for it.

Did you notice this?

I did.
But the tire size is 7.00, so more than likely it would fit on a 15" camper wheel.
Never really contemplated buying that particular tire (especially over the inter-web), but over the years I have seen that type of tire on equipment trailers.
Just ran across it while surfing and wanted to hear what others thought about it.


thanks again for the help,
Boogie