A little background. I have a 40 foot, 2009 Montana 5th wheel. The placard on the side says the GVWR is 15600+ and the tires that are suppose to be used are shown to be 235/80R16 Load Range E 10 ply tire. I have had the trailer weighed and it is anywhere from 11,000 to 13,500 pounds. I say any where because I have had it weighed several times over the last three years. I have blown several tires in the last few years. After many phone calls to many tire gurus and talking with Drexel Axle people I have come to the conclusion that I have to upgrade my tires to Load Range F 12 ply. Those tires are 235/85R16. This means upgrading the wheels also since the ones I have will only allow air pressure up to 80 pounds and the Load Range F require 95 pounds of pressure. There is no scuffing of the tires and it is suggested that there is not an alignment problem. Do you know how many trailer axle alignment businesses are out there? I haven't been able to find any very close to my location. After discussions with Drexel Axle and several tire dealers, they don't think I have an alignment problem since no specific tire or tire location fails.Basically the question is.... am I going down the right road? I have had suggestions of going to Load Range G 16 inch tires requiring 110 pounds of pressure. It has also been suggested that I go to a 19.5 tire. The G 16 and the 19.5 tires are 14 ply.Please let me know. I am going to make the change soon and the cost can be costly.

If you plan to keep the trailer for a long time get the bigger wheels and tires. (17.5")I upgraded to 16" HD wheels and G rated tires that require 110#'s of pressure several years ago. If I had it to do over I would go 17.5" because you have more tire options with heavier load ratings.

Why not contact Montana and ask them what the recommended upgrade would be? They can probably tell you. As far as tires you will get recommendations for every brand made (it seems) but all will say to stay away from the chinese made tires (good luck). Take all of it with a BIG grain of salt. There isn't a brand of tire made that hasn't had a blowout at one time or another and all get posted. The RVer's that don't have blowouts usually don't post. Keep that in mind.Asking about tires on here is like kicking a fire ant bed....

If I were going to have to buy new wheels, I would get the 17.5 inch. Much more choice in tires and I think they are cheaper. Did you look on the back side of the wheel to see what the maximum pressure was or are you assuming it is 80? My trailer came with the same size tires but my rims were rated 110 psi. I went with 235/85 16 load range G at 110 psi.

I think I would check out the 19.5 inch tires and rims. If you get the 17.5 they still will cost an arm and leg this way you get the 19.5 on the truck too and you have 2 spares and you always have a good tire or 2 when you change the truck tires. Just a thought.

dbbls wrote:If I were going to have to buy new wheels, I would get the 17.5 inch. Much more choice in tires and I think they are cheaper. Did you look on the back side of the wheel to see what the maximum pressure was or are you assuming it is 80? My trailer came with the same size tires but my rims were rated 110 psi. I went with 235/85 16 load range G at 110 psi.X2I replaced the 16" wheels and tires on my trailer with 17.5 in March and could not be more pleased. Yes.....cost some bucks, but would do it again. Have put about 3,000 miles on them and highly recommend them.

Tires Upgrade | Good Sam Community

ronniedean1234
Explorer
Aug 04, 2013
Wiley75 wrote:
I haven't worried about keeping it under 65mph with my Geostar 574s. I inflate them per the load chart for that size tire/weight and run 70-72 mph all day long without thinking twice. Even when it's 100 degrees outside. It not exactly as if once the letters "ST" are put on the side then it'll fail if you drive 65.01+ mph. I do keep my eye on them of course, as I do all of my tires, and so far so good.

X2 On the Geostar 574, have about 7000 miles on them and love em,
Me_Again
Explorer III
Aug 01, 2013
FastEagle wrote:
jjbrown6818 wrote:
A little background. I have a 40 foot, 2009 Montana 5th wheel. The placard on the side says the GVWR is 15600+ and the tires that are suppose to be used are shown to be 235/80R16 Load Range E 10 ply tire. I have had the trailer weighed and it is anywhere from 11,000 to 13,500 pounds. I say any where because I have had it weighed several times over the last three years. I have blown several tires in the last few years. After many phone calls to many tire gurus and talking with Drexel Axle people I have come to the conclusion that I have to upgrade my tires to Load Range F 12 ply. Those tires are 235/85R16. This means upgrading the wheels also since the ones I have will only allow air pressure up to 80 pounds and the Load Range F require 95 pounds of pressure.

There is no scuffing of the tires and it is suggested that tuhere is not an alignment problem. Do you know how many trailer axle alignment businesses are out there? I haven't been able to find any very close to my location. After discussions with Drexel Axle and several tire dealers, they don't think I have an alignment problem since no specific tire or tire location fails.

Basically the question is.... am I going down the right road? I have had suggestions of going to Load Range G 16 inch tires requiring 110 pounds of pressure. It has also been suggested that I go to a 19.5 tire. The G 16 and the 19.5 tires are 14 ply.

Please let me know. I am going to make the change soon and the cost can be costly.

Personally I think the 17.5” options need to be justified with your personal traveling habits. If you’re just a casual user, only doing a few thousand miles a year, the dollar value of the 17.5” rims and tires is very expensive. On the other hand, constant travel up over 15,000 miles a year would justify the expensive rims and tires.

The LT235/85R16G is manufactured in numerous brand names and is more than just adequate for your certified 6750# GAWR axles. The popular name brands may not always be easy to find, but others are, so you can often find them when most needed.

One thing to remember about that tire is its rim width. I’ve not checked the specs on all of the brand names but those that I have checked only have one acceptable rim width, 6.5”.

FastEagle

He most likely needs upgraded wheels to go the LRG 16" tires. Even you were going to skip over to 17.5's! Why would the OP not do that. Much bigger choice of tires verse three or so with 16" LRG, plus much easier to get a name brand tire. Chris
FastEagle
Explorer
Aug 01, 2013
jjbrown6818 wrote:
A little background. I have a 40 foot, 2009 Montana 5th wheel. The placard on the side says the GVWR is 15600+ and the tires that are suppose to be used are shown to be 235/80R16 Load Range E 10 ply tire. I have had the trailer weighed and it is anywhere from 11,000 to 13,500 pounds. I say any where because I have had it weighed several times over the last three years. I have blown several tires in the last few years. After many phone calls to many tire gurus and talking with Drexel Axle people I have come to the conclusion that I have to upgrade my tires to Load Range F 12 ply. Those tires are 235/85R16. This means upgrading the wheels also since the ones I have will only allow air pressure up to 80 pounds and the Load Range F require 95 pounds of pressure.

There is no scuffing of the tires and it is suggested that there is not an alignment problem. Do you know how many trailer axle alignment businesses are out there? I haven't been able to find any very close to my location. After discussions with Drexel Axle and several tire dealers, they don't think I have an alignment problem since no specific tire or tire location fails.

Basically the question is.... am I going down the right road? I have had suggestions of going to Load Range G 16 inch tires requiring 110 pounds of pressure. It has also been suggested that I go to a 19.5 tire. The G 16 and the 19.5 tires are 14 ply.

Please let me know. I am going to make the change soon and the cost can be costly.

Personally I think the 17.5” options need to be justified with your personal traveling habits. If you’re just a casual user, only doing a few thousand miles a year, the dollar value of the 17.5” rims and tires is very expensive. On the other hand, constant travel up over 15,000 miles a year would justify the expensive rims and tires.

The LT235/85R16G is manufactured in numerous brand names and is more than just adequate for your certified 6750# GAWR axles. The popular name brands may not always be easy to find, but others are, so you can often find them when most needed.

One thing to remember about that tire is its rim width. I’ve not checked the specs on all of the brand names but those that I have checked only have one acceptable rim width, 6.5”.

FastEagle
Wiley75
Explorer
Aug 01, 2013
I haven't worried about keeping it under 65mph with my Geostar 574s. I inflate them per the load chart for that size tire/weight and run 70-72 mph all day long without thinking twice. Even when it's 100 degrees outside. It not exactly as if once the letters "ST" are put on the side then it'll fail if you drive 65.01+ mph. I do keep my eye on them of course, as I do all of my tires, and so far so good.
Me_Again
Explorer III
Aug 01, 2013
BeerCan wrote:
I think it is similar to the Sailun. The Sailun is a LT tire but has "for trailer use only" molded into the sidewall. That could be argued that makes it an ST tire. Geostar probably just labeled it an ST to indicate it is also for trailer use only. Just my speculation.

That would give them the 65MPH speed restriction by industry standards, which is maybe what they wanted! Chris
BeerCan
Explorer
Aug 01, 2013
I think it is similar to the Sailun. The Sailun is a LT tire but has "for trailer use only" molded into the sidewall. That could be argued that makes it an ST tire. Geostar probably just labeled it an ST to indicate it is also for trailer use only. Just my speculation.
Me_Again
Explorer III
Aug 01, 2013
BeerCan wrote:
Me Again wrote:

When someone finally makes a ST tire that will handle a large trailer it will cost and look a lot like a good commercial tire that is available today!

Chris

Here is a reportedly good all steel ST tire. It was the only one I could find when I was researching for my trailer. It has many good reports but YMMV

Geostar G574

That tires load rating and inflation matches up to a LRG LT type tire industry standard load rating. It does not have the inflated ratings of the bunch of 35 pounds that cause all the problems.

Actually some sites list it as a LT tire. Their own web site has it under Steer/Highway.
http://geostartrucktire.com/tires/steerhighway/

I do not believe that it is a Service Trailer(ST) tire like the ones that give so many problems.

Chris
BeerCan
Explorer
Aug 01, 2013
Me Again wrote:

When someone finally makes a ST tire that will handle a large trailer it will cost and look a lot like a good commercial tire that is available today!

Chris

Here is a reportedly good all steel ST tire. It was the only one I could find when I was researching for my trailer. It has many good reports but YMMV

Geostar G574
Me_Again
Explorer III
Aug 01, 2013
samandtheduck wrote:
Mine has 7k axles and had load range E tires at 80 psi on it but the rims were rated at 110 psi. I tried the Carlisle load range F and blew two of them. I then bought the 17.5 inch rims and Sumitomo tires (load range H) for $550 each ($2200 total) and am very happy with them. If I had skipped the Carlisles altogether I would be even happier.
Brian

Sooner or later people figure out that cheap ST tires are just that! They are a tire type that was created for local use on utility type trailers that somehow found their way onto large RV trailers with little or no changes in how they are made.

When someone finally makes a ST tire that will handle a large trailer it will cost and look a lot like a good commercial tire that is available today!

Carlisle and TowMax lay claim to new Nylon overlays that are going to fix their ST tires. I asked Goodyear about that on their Marathon and they said it was added years ago to the Marathon, so I lay little hope that a fix was found by these two.

If you are going to see America, do NOT try it on cheap tires!

Chris
samandtheduck
Explorer
Aug 01, 2013
Mine has 7k axles and had load range E tires at 80 psi on it but the rims were rated at 110 psi. I tried the Carlisle load range F and blew two of them. I then bought the 17.5 inch rims and Sumitomo tires (load range H) for $550 each ($2200 total) and am very happy with them. If I had skipped the Carlisles altogether I would be even happier.
Brian

Forum Discussion

Tires Upgrade

About Fifth Wheel Group

Related Content

Tire upgrade

Tire upgrade air preasure?

tire size upgrade

Weekend Warrior FS2300 2006 wheel tire upgrade

Suspension Upgrades