Wanting to change from STs to LTs..........

[Paulb1310]

We are the proud new owners of a 2007 K-Z Sportsman 5th wheel. The unit is in EXCELLENT shape for its age. This is our first (but likely won't be our last).

I have read numerous posts on the arguments of STs versus LTs. My conclusion is the I am going to replace the current tires/wheels with larger, more robust ones.

Here is what I currently have:
Tire: Load Max Radial
Tire Size: ST225/75R15
Overall diameter: 28.3"
Rim width range: 6-7"
Date Code: 614 0906 (waaaaay old!)
Wheels: Six bolt on 5.5" centers
Load rating for each tire: 2540 pounds
GVWR for trailer: 10,000 pounds

Here is what I want:
Tire: Michelin LTX A/T 2
Tire Size: LT245/75R16
Rim width range: 6.5-8"
Overall diameter: 30.5"

Wheel Choice #1: HiSpec Series 04
Wheel Size: 16x7
Wheel load rating: 3200
Offset: +5mm

Wheel Choice #2: HiSpec Series 05
Wheel Size: 16x6.5
Wheel load rating: 3580 pounds
Offset: 0mm

So, what have I considered so far?

1. Separation between current tires is 5.0". By using this size tire the separation would be 2.8". This would appear to be sufficient.

2. Currently there is 6" of suspension travel between the top of the tire and the floor of the 5th wheel. This would be reduced to 4.9". This, too, seems sufficient.

3. The passenger side shocks currently sit 3/4" away from the tire. This might be dicey with a bigger tire and wheel. If the tire is too close the options are to (a) put a spacer between the wheel and the hub with longer lug nuts or (b) move the shock to the other side of the axle (likely NOT a good option.)

4. The passenger side front tire is close to the fender. I could (a) trim off part of the fender or (b) install a brace underneath to push the fender our a few tenths of an inch or (c) a combination of (a) and (b).

5. The top of the tire to the bottom of the fender is 3.5". I don't know just how much more the bigger tires would protrude. Of course, the current tires don't have a problem with hitting the inside edge of the fender. I'm not sure if the bigger tires would have an issue or not.

So, what have I missed?


Thanks for your help!!

Paul.

[AH64ID]

Me Again wrote:

ah64id wrote:

Me Again wrote:

ah64id wrote:
Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

I thought it was over chart but not to exceed max sidewall?

Chris

The press release I saw says 10psi above the placard limit, if the wheels and valve stems are rated for it. There is nothing that limits that pressure to the sidewall pressure.

So you know this is the 5th wheel section and they seem to be much harder on cheap ST tires, right?

So you know weight ratings are the same regardless of the trailer they are on...

A 5er with a 10K GVW will have less weight on the tires than a 10K GVW TT, and they both "should" have 5,200's and LRD tires. Mfgrs may cut corners here, not the tires fault.

[ol_Bombero-JC]

ah64id wrote:
Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

Many/some of "us" who had TTs in the past - also had Marathons.

They did just fine on my previous 20' & 24' Terry TTs.
(However, I switched to non-GY LT tires on the 24 long before I sold it.)

Many are/were aware of the GY 10psi "permitted" increase.
GY made that one disappear - although it still can be found out there in cyberspace.
That may have been about the time they lost the lawsuit, which included Marathons for RV use. (Google: "Goodyear kept tire problems quiet")

As already noted - 5th wheels and ST tires are *not* a good combo!

Since you are a TT guy, here's a lengthy thread from the Airstream forums about your tire choice..:C

Seems a lot of the Airstream TT owners do *NOT* share your warm feelings for Goodyear Marathons on their TTs..:(

It should be termed.... a *Marathon* about - GY Marathons!...:B

Air Forums: "Goodyear Marathon Failures"

BTW it ran from 11-29-06 to 5-3-2011, then to a link for a poll at post #678 - which continues in a new thread with comments/posts thru 2014.

Apparently a "never ending" saga!..:R

Maybe you should post your success story there for a comparison..:@



~

[Me_Again]

ah64id wrote:

Me Again wrote:

ah64id wrote:
Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

I thought it was over chart but not to exceed max sidewall?

Chris

The press release I saw says 10psi above the placard limit, if the wheels and valve stems are rated for it. There is nothing that limits that pressure to the sidewall pressure.

So you know this is the 5th wheel section and they seem to be much harder on cheap ST tires, right? Your bumper pull is much lighter than most 5th wheels running ST tires to early failure.

[AH64ID]

Me Again wrote:

ah64id wrote:
Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

I thought it was over chart but not to exceed max sidewall?

Chris

The press release I saw says 10psi above the placard limit, if the wheels and valve stems are rated for it. There is nothing that limits that pressure to the sidewall pressure.

[Me_Again]

ah64id wrote:
Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

Got to watch your wheels. This thread has a link to the document.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27174748/gotomsg/27191698.cfm#27191698

Many ST235/80R16E are mounted on wheels rated to only 80 lbs, therefore you can not increase inflation to 90.

The whole premise of this flies in the face of the fact that they fail way to often at 65 mph and below already.

Chris

[AH64ID]

Goodyear allows the Marathon ST tires to run 10psi over the chart or sidewall pressure, which increases the speed rating from 65 to 75.

I am on my 2nd TT and they have been on both, lots of miles and rough road miles. I haven't had any issues I can blame the tires for, just 2 flats from rock punctures on some nasty forest service roads.

I will need new tires next year and will go back to the 225/75R15 Marathon in LRD, I max them out at around 80% of their load rating.

[Me_Again]

Paulb1310 wrote:
I do have one final question: Do these tires have a speed rating on them?

The XPS Rib carries a service description. And is rated to 99 mph for pickups and commercial trucks. For RV use Michelin states 75 mph. Chris

[Paulb1310]

I do have one final question: Do these tires have a speed rating on them?

[Paulb1310]

Well, I finally made a decision. After a BUNCH of research and consideration, I decided on the HiSpec S5 aluminum wheels (rated 3580 pounds) and the Michelin XPS Rib LT245/75R16.

And yes, I DO understand this is way overkill for this trailer. But these tires and wheels will outlast this trailer. I plan on keeping the current old tires and wheels in dry storage and putting them back on when we decide to trade.

My only slight concern is the clearance from the inside of the tire to the shocks. The original clearance was 13/16". The new clearance with the XPS Ribs are 11/16". I seriously doubt this 1/8" will make much difference.

There are a couple of areas where I will have to cut off a bit of trim, but this is pretty minor and will be unnoticeable.

Michelin publishes a guide of tire pressures based on tire load. (This is linked somewhere else in this thread.) At the loading I will be placing on these tires, I will likely run 50-55 PSI.

So, a hearty "THANK YOU!!" for all those that supplied their time and wit to this thread.

[gitane59]

bpounds wrote:

jaycocamprs wrote:

Why would anyone need G rated tires on a trailer with 5200# axles?

Good point, to which I would add, why would anyone need LT tires on a trailer with 3,500# axles, which a 10k trailer is likely to have. Or at best 4,400# axles.

I certainly hope there are no 10K lb fiver's out there with 3500 lb axles as 20% pin weight would equal 2K lbs and with 3500 lb axles that leaves your trailer's axles and brakes 1000 lbs overloaded.

[Allworth]

I hope the OP (and others) has learned that when wanting to make a tire decision; JUST DO IT! Don't let it become a Forum Thread. You will die of old age before the discussion is over.

[bpounds]

jaycocamprs wrote:

Why would anyone need G rated tires on a trailer with 5200# axles?

Good point, to which I would add, why would anyone need LT tires on a trailer with 3,500# axles, which a 10k trailer is likely to have. Or at best 4,400# axles.

[Cummins12V98]

jaycocamprs wrote:

MM49 wrote:
I wouldn't recommend a LT tire, but if you are determined to, the Hercules H-901 looks like an interesting G rated, all steel tire.
MM49

Hercules Tire

Why would anyone need G rated tires on a trailer with 5200# axles? When I did a swap on a 9K trailer, any more than 70psi in a BFG LT235/85R16/E would not make contact across tread. Those tires lasted 5 years, 2 on the JayFlight, 3 on the Mountaineer. I replaced them with R250's this summer

We have a winner!!!!!!

When changing to a higher load rating tire use the tire weight/inflation chart to properly air your tires. Don't just blindly fill tires to MAX PSI!

[Me_Again]

MM49 wrote:


I wouldn't recommend a LT tire, but if you are determined to, the Hercules H-901 looks like an interesting G rated, all steel tire.
MM49

Hercules Tire

MM49 remind us again what make and model 5th wheel you have and a little on your tire experience with it. What does it weigh? Chris

[P_Kennedy]

Because ST tires have never proven to be superior in mileage, performance in adverse conditions on commercial light trailing equipment. Because LT commercial tires are used in higher speed adverse conditions with less failures despite serious side torqueing in tight turns. Because my Bridgestone R250 LT tires run cooler and squirm less on rutted pavement than ST "gotta be there" according to RV tire guru's. Because my tire guy is the same guy who supported my class 8 trucks through the barrage of lies from tire manufacturers with all the answers on my dime. Because $1200.00 worth of quality under my $40k rig is cheap compared to the experiences of the china bomb and other ST only rv victims. Michelin Ribs are an all position commercial tire, Bridgestone R250 are a commercial all position tire and there is a few more out there. ST tires are trailer only 65 mph max speed tire, with the increase in highway speeds nation wide we will see increased ST tire failures. Hope there not near me when they fail because most of the high speed idiots pulling trailers don't care what they have under their rigs nor do they care they just want to get there fast.