Should I get a higher load rated tire?

[Lic0rice]

Just purchased a Montana 3400RL. It came with like new Cooper Discoverer HTP tires which have a load rating of 3042lbs (correction:3086#). Loaded, the Montana will weight approximately 14K. With a tongue weight of 2300lbs, I think I'm pushing the limit. Should I be tire shopping?

[Ken / Claudia]

A great idea for many reasons would be to load up and go to a scale check truck and trailer get real weights. We do not know if the trailer or tires are new or used. If tires are used check the date code. If 3 to 5 years old you might want to get new tires anyway.

[Lic0rice]

A great idea for many reasons would be to load up and go to a scale check truck and trailer get real weights. We do not know if the trailer or tires are new or used. If tires are used check the date code. If 3 to 5 years old you might want to get new tires anyway.

Excellent suggestion of actually weighing the trailer!!!

Tires were purchased new 18 months ago. Seller furnished receipt.

[notanlines]

"check the date code" ^^^what Ken said. There is an absolute cornucopia of information available (I like that word) at your friendly CAT scale. Therein lies
the secret to weight distribution and what the tires are supporting. Keep us posted.

[CWtheMan]

Just purchased a Montana 3400RL. It came with like new Cooper Discoverer HTP tires which have a load rating of 3042lbs. Loaded, the Montana will weight approximately 14K. With a tongue weight of 2300lbs, I think I'm pushing the limit. Should I be tire shopping?

What year model is your Montana? Year models 2004 & 2005 3400RL Montana models had OEM LT235/85R16E tires. All later models had ST235/80R16E tires. Some of the 2003 and earlier models had ST235/80R16D tires.

It’s a misapplication to use replacement tires with less load capacity than the Original Equipment tires identified on the trailer’s certification label or tire placard.

http://us.coopertire.com/Tire-Safety/Replacement-Tire-Guide/Load-Capacity.aspx

[Lic0rice]

What year model is your Montana? Year models 2004 & 2005 3400RL Montana models had OEM LT235/85R16E tires. All later models had ST235/80R16E tires. Some of the 2003 and earlier models had ST235/80R16D tires.

It’s a misapplication to use replacement tires with less load capacity than the Original Equipment tires identified on the trailer’s certification label or tire placard.

http://us.coopertire.com/Tire-Safety/Replacement-Tire-Guide/Load-Capacity.aspx

2006 - specs show 235/80R16E. These are 85E but that seems to be pushing the higher load range but no idea about the brand/type.
ETA: 3086# is their load limit

[cw3jason]

My tires are rated for 3520 at 80psi. I had my Montana weighed with individual wheel scales and 1 wheel was as high as 3125lbs. total trailer weight of 14,075.

Yes I believe your tires are not up to the challenge of supporting the weight of a 14,000lb Montana and should be replaced.

[CWtheMan]

2006 - specs show 235/80R16E. These are 85E but that seems to be pushing the higher load range but no idea about the brand/type.
ETA: 3086# is their load limit

Your trailer was probably equipped with the Goodyear Marathon ST tires. They did not have a very good reputation 10 years ago and some owners still shy away from them.

You should go back to using ST235/80R16E tires. Properly maintained they are appropriate for your weight and are the correct fitment so your rims should already qualify for them.

Some owners unfamiliar with trailer tires see a LRE LT as being equal to a LRE ST tire. However, the maximum load capacity of the LT235/85R16E is 3042# @ 80 PSI and the maximum load capacities for the ST235/80R16E tires can be 3420#, 3500# and 3520# depending on manufacturer (all @ 80 PSI) . There is no other way to figure strength for a tire regardless of design.

By the way, that 3086# load limit you posted above is from the tire's load index value section of the tire's service description. It's authorized to be on the tire's sidewall for other reasons such as the speed letter. The only DOT approved load capacity values for LT & ST tires are their load range letters.

An equal comparison of load capacity by design is found using the LT235/85R16E rated at 3042# @ 80 PSI against the ST235/85R16E rated at 3640# @ 80 PSI.

[Lic0rice]

Your trailer was probably equipped with the Goodyear Marathon ST tires. They did not have a very good reputation 10 years ago and some owners still shy away from them.

You should go back to using ST235/80R16E tires. Properly maintained they are appropriate for your weight and are the correct fitment so your rims should already qualify for them.

Some owners unfamiliar with trailer tires see a LRE LT as being equal to a LRE ST tire. However, the maximum load capacity of the LT235/85R16E is 3042# @ 80 PSI and the maximum load capacities for the ST235/80R16E tires can be 3420#, 3500# and 3520# depending on manufacturer (all @ 80 PSI) . There is no other way to figure strength for a tire regardless of design.

By the way, that 3086# load limit you posted above is from the tire's load index value section of the tire's service description. It's authorized to be on the tire's sidewall for other reasons such as the speed letter. The only DOT approved load capacity values for LT & ST tires are their load range letters.

An equal comparison of load capacity by design is found using the LT235/85R16E rated at 3042# @ 80 PSI against the ST235/85R16E rated at 3640# @ 80 PSI.

Excellent info! Any recommendation on specific ST brand?

[CWSWine]

Just purchased a Montana 3400RL. It came with like new Cooper Discoverer HTP tires which have a load rating of 3042lbs (correction:3086#). Loaded, the Montana will weight approximately 14K. With a tongue weight of 2300lbs, I think I'm pushing the limit. Should I be tire shopping?

That Montana will be somewhere north of 3,000lbs on the pin so that leaves about 11,000 on the 5er axles. Take 11,000 and divide by 4 gives you 2750 per tire if evenly loaded which will never happen in the real world. There is no way a Montana at 14,000 lbs will have a 16% pin weight, more like a 22 to 23% or 3080 to 3220 lbs.

[CWtheMan]

Excellent info! Any recommendation on specific ST brand?

I avoid doing brand recommendations.

Do some shopping. Find out who has valid warranty coverage and are they going to be available in your traveling areas.

Third party warranty coverage will do you no good when you're a thousand miles away when help is needed.

Some of the nation wide discount stores will provide limited warranties for road hazards on all tires they sell.

On Edit: Our Everest is 14,100# GVWR. We always travel heavy with 11,400# - 11,500# evenly distributed on our axles. Every time we scale it the hitch weight is between 2600# - 2700#. However, our washer dryer combo is on the main floor level near the forward axle and we never carry more than 15 gallons of water (total). Our tires provide us with about 22% in load capacity reserves when new. They are rated at 3520# and are inflated to 80 psi.

[cw3jason]

Most Montana owners are putting Goodyear G614's or Sailun S637's on there rigs to support that kind of weight.

[Lic0rice]

Most Montana owners are putting Goodyear G614's or Sailun S637's on there rigs to support that kind of weight.

I've been looking at the Sailuns. Spoke to a local dealer who I get all my commercial truck tires from. He recommends Hercules H-901. Says that they have steel belted side walls and he has put a lot of them on 5th wheels, horse trailers, etc and never had an issue. $156 plus tax out-the-door w/steel valve stems.

[cw3jason]

I've been looking at the Sailuns. Spoke to a local dealer who I get all my commercial truck tires from. He recommends Hercules H-901. Says that they have steel belted side walls and he has put a lot of them on 5th wheels, horse trailers, etc and never had an issue. $156 plus tax out-the-door w/steel valve stems.

I haven't heard of the Hercules, I will have to look into them.

[CWtheMan]

Most Montana owners are putting Goodyear G614's or Sailun S637's on there rigs to support that kind of weight.

Your trailer should have already been equipped with something like those tires. They would be a requirement for 7000# axles.

Other Montana's may have 7000# axles derated to 6750# so they can be fitted with the ST235/80R16E tires. Although those tires meet the minimum requirements for the derated axles they wont last long on a fully loaded trailer.

[CWtheMan]

I haven't heard of the Hercules, I will have to look into them.

Once the GY G614 became so successful on 7000# axles the "over there" manufacturers jumped on the band wagon. The first ones on the market (Sailun) got good reviews and are very popularly recommended. They are all basically the same tire, steel cased with 3750# of load capacity @ 110 PSI. So warranty coverage and availability should be high on your approval list.

[Lic0rice]

Your trailer should have already been equipped with something like those tires. They would be a requirement for 7000# axles.

Other Montana's may have 7000# axles derated to 6750# so they can be fitted with the ST235/80R16E tires. Although those tires meet the minimum requirements for the derated axles they wont last long on a fully loaded trailer.

Our Montana is a 2006 model. The original specs indicate that it came with 235/80R/16E but it now sits on 235/85R/16E. I my view, both setups are inadequate. I'm looking for a quality G or H rated tire. Loaded we will top 14k with about 11,500 of that on the TT tires.

I'm new to this and relying on what I read in various forums and a discussion with the tire company that handles my company vehicles. Based on what I've read & heard, my best option will be to equip the TT with wood sleds and just drag it because there are no tires on the market that are worth a hoot!! :eek:

[cw3jason]

Your trailer should have already been equipped with something like those tires. They would be a requirement for 7000# axles.

Other Montana's may have 7000# axles derated to 6750# so they can be fitted with the ST235/80R16E tires. Although those tires meet the minimum requirements for the derated axles they wont last long on a fully loaded trailer.

The Montana's come with the E rated tires specified above and as you stated meet minimum requirements. It is an upgrade to go to G rated tires such as the GY614 or S637. It is definitely worth the upgrade for peace of mind.

[CWtheMan]

The Montana's come with the E rated tires specified above and as you stated meet minimum requirements. It is an upgrade to go to G rated tires such as the GY614 or S637. It is definitely worth the upgrade for peace of mind.

Keystone may have violated federal regulations by fitting your trailer with ST235/80R16E tires. According to their internet specs for your trailer it has 7000# axles and because of the specs Keystone must set your GAWRs at 7000#. Without specifying a specific tire for those GAWRs the certification label would be in error. The reason for that is there are ST235/80R16E tires such as Maxxis and Goodyear that only provide a maximum of 3420# of load capacity and do not qualify for fitment on 7000# axles. So if your certification label says 7000# GAWR for each axle and list ST235/80R16E as a proper fitment without explanation Keystone has made an error in fitment or misprinted the certification label. Doing the math with the specs leaves no room for derating the axles. Its a catch 22 safety violation and you should get an explanation from Keystone as to how they have justified your tire fitments without an explanation.

Here is how I did the math on your trailer's specs;

SW = 12805
CCC = 3660

GVWR = 16565
Hitch weight = 2565
Minus Hitch weight = 14000

Divide by 2 = 7000# -- That's the minimum axle requirement according to their specs.

[cw3jason]

Axles are 7000 and tires are rated for 3520. Like I said they just meet the spec, but should be replaced due to tire degrading 10 percent a year.

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[Lic0rice]

Keystone may have violated federal regulations by fitting your trailer with ST235/80R16E tires. According to their internet specs for your trailer it has 7000# axles and because of the specs Keystone must set your GAWRs at 7000#. Without specifying a specific tire for those GAWRs the certification label would be in error. The reason for that is there are ST235/80R16E tires such as Maxxis and Goodyear that only provide a maximum of 3420# of load capacity and do not qualify for fitment on 7000# axles. So if your certification label says 7000# GAWR for each axle and list ST235/80R16E as a proper fitment without explanation Keystone has made an error in fitment or misprinted the certification label. Doing the math with the specs leaves no room for derating the axles. Its a catch 22 safety violation and you should get an explanation from Keystone as to how they have justified your tire fitments without an explanation.

Here is how I did the math on your trailer's specs;

SW = 12805
CCC = 3660

GVWR = 16565
Hitch weight = 2565
Minus Hitch weight = 14000

Divide by 2 = 7000# -- That's the minimum axle requirement according to their specs.

NOT just the axles.....the wheels are marked Max Single Load 3042# and 80psi max. :rtfm:

I thought that I would go with Sailun S637 but they are rated at 110psi/4080#.

Would I be best to just buy new wheels? Don't mind doing that if it will solve the issue. I am not comfortable with any of the ST tires that are rated to 80psi.

[cw3jason]

NOT just the axles.....the wheels are marked Max Single Load 3042# and 80psi max. :rtfm:

I thought that I would go with Sailun S637 but they are rated at 110psi/4080#.

Would I be best to just buy new wheels? Don't mind doing that if it will solve the issue. I am not comfortable with any of the ST tires that are rated to 80psi.
Look at the back of your wheels. The Montana's are coming with 110psi rated rims, I do not know the year or model of your Montana, but if it's fairly new, you may have the rims you need and can just get a set of Sailuns mounted and balanced.

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[cw3jason]

Look at the back of your wheels. The Montana's are coming with 110psi rated rims, I do not know the year or model of your Montana, but if it's fairly new, you may have the rims you need and can just get a set of Sailuns mounted and balanced.

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It really sounds like someone put the wrong tires on your rig. Maybe the previous owner? I know my Montana came with wheels rated for 3520 and I still want to change them to. G rated tire.

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[Lic0rice]

Look at the back of your wheels. The Montana's are coming with 110psi rated rims, I do not know the year or model of your Montana, but if it's fairly new, you may have the rims you need and can just get a set of Sailuns mounted and balanced.

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They may be coming with those wheels now but my '06 wheels say 80psi/3042lbs. The original owner says those are the wheels that came on it new.

[cw3jason]

They may be coming with those wheels now but my '06 wheels say 80psi/3042lbs. The original owner says those are the wheels that came on it new.
Got it. You definitely need an upgrade

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[CWtheMan]

Axles are 7000 and tires are rated for 3520. Like I said they just meet the spec, but should be replaced due to tire degrading 10 percent a year.

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Technically your tires rated at 3520# do meet the minimum requirement for 7000# GAWR axles. By the "book" they do not, without documentation from Keystone to NHTSA. Keystone must inform NHTSA they are using ST235/80R16E tires that meet the minimum requirements for GAWR 7000# axles.

Because of another NHTSA regulation that says in part that when tires of an identical size and construction having more than one load capacity at a given psi they must all default to the lowest value. The ST235/80R16E tires are manufactured in three different maximum load capacities, 3420#, 3500# and 3520#, all @ 80 psi. For one to properly fit replacements for your trailer they would match the information found on the certification label, tire placard or in the owner's manual. See where I'm coming from? Keystone has often overlooked the problem with that size tire and has had to recall certification labels because of it. You should aske them to do it again.

[Lic0rice]

OK, I get the tire issue but I still have 2 simple questions regarding the rims which I see as two separate issues:

1) Is it safe/smart to run tires marked "Max Load 3520 - Max psi 80" on a rim marked "Max Single Load 3042# - 80psi Max" ?

2) Is it safe/smart to use rims marked Max Single Load 3042# on a Montana 3400RL ?

[dcg9381]

Are your tires rated for 3520 @ 80 psi?


1) That means your rims will have a load failure before your tires will. I expect that a rim failure is likely much more catastrophic than a tire failure - but you're improving the tire situation.

2) A 2015 3400RL has a shipped weight of 12710, with a GVWR of 16715. Pin weight, 2715.

Roughly, loaded, 16715 - 2715 = 14000 lbs, 3500 lbs per tire (if loaded evenly). Might be slightly better situation, as the pin will take some of that load... I would say at GVWR (max loaded weight) you should not run wheels rated for 3042.

[Lic0rice]

Are your tires rated for 3520 @ 80 psi?


1) That means your rims will have a load failure before your tires will. I expect that a rim failure is likely much more catastrophic than a tire failure - but you're improving the tire situation.

2) A 2015 3400RL has a shipped weight of 12710, with a GVWR of 16715. Pin weight, 2715.

Roughly, loaded, 16715 - 2715 = 14000 lbs, 3500 lbs per tire (if loaded evenly). Might be slightly better situation, as the pin will take some of that load... I would say at GVWR (max loaded weight) you should not run wheels rated for 3042.

That confirms exactly what I was thinking. Unless someone talks me off the ledge, I'm purchasing new rims and Saulin S637 with a Load Range "G".

Thanks for all the help!!

ETA: The 2006 specs for a 3400RL is 11,650# shipping weight and 1975# tongue weight. Even with those lower numbers, I need new wheels and G rated tires.

[cw3jason]

That confirms exactly what I was thinking. Unless someone talks me off the ledge, I'm purchasing new rims and Saulin S637 with a Load Range "G".

Thanks for all the help!!

ETA: The 2006 specs for a 3400RL is 11,650# shipping weight and 1975# tongue weight. Even with those lower numbers, I need new wheels and G rated tires.
I believe you have made a wise choice

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