Is Tire Placard Wrong

mhbell · 04-30-2018, 06:49 PM

The Tire Placard on my 5th wheel states that the ST 225/75R15 tire inflation pressure should be 65 Lbs PSI. When checking the tire pressure I found that it was 80 Lbs PSI in all 4 tires on my 5th wheel. I thought, Oh No the dealer put to much air in the tires. The Tires That came with the trailer are TowMax Power King STR ST 225/75R15 load range E. Before I would Lower the pressure I did some checking and found that there are two versions of this tire. One is load range D with a single tire load of 2540 Lbs at 65 Lbs PSI which would give a carrying capacity of 4 X 2540 Lbs 4 tires 2 axles = 10,160 Lbs. The max load of the trailer GVWR is 10,000 Lbs which only leaves 160 Lbs for safety. The tires on the trailer are Load range E with a carrying Capacity of 2830 Lbs at 80 lbs PSI. So the max load for the tires would be 4 X 2830 4 tires 2 axles = 11,320 Lbs, which would give a safety factor of 1,320 Lbs. I will not lower the pressure to 65 Lbs because years ago I lost 3 tires out of 4 on a Jayco Designer 5th wheel because of under inflation. I am glad I got the tire spec's before doing anything. I will keep the tires inflated at 80 Lbs PSI. But the placard says 65 Lbs PSI. I wonder if the trailer is placarded wrong.
Mel

Ken / Claudia · 04-30-2018, 07:02 PM

Sounds like someone put on Es instead of Ds. Not sure were you got the research data but, it is all on the tire sidewall. Go by what is printed on them is my advice.

**sourdough** · 04-30-2018, 07:17 PM

My trailer came with the load range D (same size) - 10,160 maxed with a 10k gvw load. Blew out one tire on my 2nd trip. Went to Carlisle Radial Trail HD LRE and increased my joad rating and my safety margin....3 yrs, no problem, look new. If you got the LRE when the placard said LRD...you got a big break. Run them at 80 psi....but, they are TowMax...ie; blow max!! IMO you need to look at replacing them as soon as you can....do a search of the forum.

**chuckster57** · 04-30-2018, 07:19 PM

If you look at the placard, that may be the tires originaly put in service. The tires don’t carry the full weight of the trailer, up to 20% is on the kingpin so the placard May be correct.

Is it possible that someone changed the tires to the higher load/inflation?

mhbell · 04-30-2018, 07:48 PM

Quote:

Originally Posted by chuckster57

If you look at the placard, that may be the tires originaly put in service. The tires don’t carry the full weight of the trailer, up to 20% is on the kingpin so the placard May be correct.

Is it possible that someone changed the tires to the higher load/inflation?

I guess it is possible, but with solar panels and 4 trojan batteries, The previous owner may have switched. I am right at 9,800 + pounds Loaded. So am glad to have the extra margin and load capacity. The only tire failures that I have ever had in 50 plus years of RVing, were all USA made Goodyear tires and one Michlin. 3 of the failures were my fault because of under inflation and driving to fast on ST type tires.
Mel

**JRTJH** · 05-01-2018, 05:47 AM

My 2014 Cougar XLite 27RKS came with 225 75R15 LRD tires. The max pressure is 65PSI and is correctly reflected on the trailer placard. I upgraded (as many have) to 225 75R15 LRE tires (80 PSI) last year. My trailer placard has not been changed and still reflects the OEM tire standards.

With the trailer GVW of 10,000 pounds and 1800 pounds on the pin when fully loaded, that leaves 8200 pounds on the axles/tires. Divided by 4 tires, that is an approximate load of 2050 per tire. With the LRD tires (2540) that is a "reserve capacity of about 490 per tire" or about 1960 for 4 tires. That's almost a 2000 pound reserve capacity on LRD tires. They weren't "close to max capacity" but with LRE tires, that reserve is even greater. And, in my opinion, a welcome safety factor.

Looking at the specs on your trailer, the OEM tire size is 225 75R15 LRD, so my guess is that either the previous owner or the dealer (before you purchased the trailer) upgraded to LRE tires.

I'd run them at max pressure (as reflected on the tire sidewall), 80 PSI, and not consider lowering the pressure.

mhbell · 05-01-2018, 07:44 AM

Quote:

Originally Posted by JRTJH

My 2014 Cougar XLite 27RKS came with 225 75R15 LRD tires. The max pressure is 65PSI and is correctly reflected on the trailer placard. I upgraded (as many have) to 225 75R15 LRE tires (80 PSI) last year. My trailer placard has not been changed and still reflects the OEM tire standards.

With the trailer GVW of 10,000 pounds and 1800 pounds on the pin when fully loaded, that leaves 8200 pounds on the axles/tires. Divided by 4 tires, that is an approximate load of 2050 per tire. With the LRD tires (2540) that is a "reserve capacity of about 490 per tire" or about 1960 for 4 tires. That's almost a 2000 pound reserve capacity on LRD tires. They weren't "close to max capacity" but with LRE tires, that reserve is even greater. And, in my opinion, a welcome safety factor.

Looking at the specs on your trailer, the OEM tire size is 225 75R15 LRD, so my guess is that either the previous owner or the dealer (before you purchased the trailer) upgraded to LRE tires.

I'd run them at max pressure (as reflected on the tire sidewall), 80 PSI, and not consider lowering the pressure.

I agree with you 100 percent John. My pin weight is 2200 Lbs. 4 trojan batteries and other solar stuff in the front storage compartment. Yes the LRE's are much better for safety margin.
Mel

notanlines · 05-01-2018, 01:53 PM

Melvin, let me continue to open a can of worms that Sourdough cracked open a couple posts back. "TowMax Power King" This name says it all. I suspect that Chuckster and John were biting their tongue when they did their posting, trying to solve one problem at a time. This is a terrible brand of tires; as evidenced by countless postings on this and many, many others. I concur with what Sourdough said: Run, do not walk, to the tire dealer. Most on here would side with Sailun, Maxxum, or Carlisle. Goodyear's new RV tire might also be acceptable, but no Marathons. I realize it is easy for me to spend your money, but what I'm telling you will put a smile on your insurance carrier's face.

mhbell · 05-04-2018, 06:59 PM

Quote:

Originally Posted by notanlines

Melvin, let me continue to open a can of worms that Sourdough cracked open a couple posts back. "TowMax Power King" This name says it all. I suspect that Chuckster and John were biting their tongue when they did their posting, trying to solve one problem at a time. This is a terrible brand of tires; as evidenced by countless postings on this and many, many others. I concur with what Sourdough said: Run, do not walk, to the tire dealer. Most on here would side with Sailun, Maxxum, or Carlisle. Goodyear's new RV tire might also be acceptable, but no Marathons. I realize it is easy for me to spend your money, but what I'm telling you will put a smile on your insurance carrier's face.

I can only give you my experience in over 50 years of RVing. THe only tire failures on a RV that I have had were american made tires and, mostly my fault because of under inflation or driving to fast with ST type tires. With that said I've never had a failure with any china made tire on a RV. I have had Salums, Samsons, carlyle, and two sets of TowMax Power kings. Never had a problem. I keep my tires at the proper inflation and don't drive over 65 MPH. The last set of TowMax that I had were on a 38 Foot Jayco Designer that I made several 2200 mile round trips to Texas in all kinds of weather. Never had a problem with them. I also have a TPMS. I feel that as long as I keep the correct tire pressure and drive between 55 and 60 I will have no problems. I know all about the so called China Bombs.
Mel

CWtheMan · 05-04-2018, 10:26 PM

The tire size is ST225/75R15. The load range is not included in the tire size. The LRD and LRE for that tire size uses an identical load inflation chart so the tire placard is still correct at 65 PSI. That's what the manufacturer said was appropriate for that fitment. However, an increase in inflation pressure somewhere between 65 - 80 PSI will provide more load capacity reserves from the LRE tires. The wheels have to be approved for the increased inflation pressure as should the valve stems.

The PSI rating on a tire's sidewall is the amount of cold inflation pressure needed for the tire to provide it's maximum load capacity. The recommended cold inflation pressure on a tire placard is the minimum acceptable inflation pressure for that particular fitment.

mhbell · 05-05-2018, 08:18 AM

Quote:

Originally Posted by CWtheMan

The tire size is ST225/75R15. The load range is not included in the tire size. The LRD and LRE for that tire size uses an identical load inflation chart so the tire placard is still correct at 65 PSI. That's what the manufacturer said was appropriate for that fitment. However, an increase in inflation pressure somewhere between 65 - 80 PSI will provide more load capacity reserves from the LRE tires. The wheels have to be approved for the increased inflation pressure as should the valve stems.

The PSI rating on a tire's sidewall is the amount of cold inflation pressure needed for the tire to provide it's maximum load capacity. The recommended cold inflation pressure on a tire placard is the minimum acceptable inflation pressure for that particular fitment.

Yes I got the information from the Tire manufacture. I have steel valve stems because I use a TPMS.
Mel

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