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Old 08-31-2015, 01:32 PM   #1
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Tire Spec Question

Thanks for the previous replies.

After weighing everything and leaving headroom I am shopping for tires to replace the Bridgestone Marathon 235/80/R16 Tires.

Of special note is I want something with a load index minimum of 129, which is 4079 lbs. (don't need anything near 5K as I estimated previously).

Would like:

(1) Minimum Load Index 129 - 4,000lbs or more.
(2) Long run tires that will last pulling back and forth across the country before I have to replace them.
(3) Fits the existing 16" rim of the Cardinal 3875
(4) Ideally made in USA not Asia
(5) Good price-performance ratio. Don't mind investing but do not want overkill


Conceivably these will be G rated or better and I'm presuming will run a higher pressure of 95 or more than the 80 the Marathon's do. I have a 150lb compressor on the truck with 50' hose and tools.

Recommendations appreciated.

I'm in OK City right now and calling around.
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Old 08-31-2015, 03:48 PM   #2
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There are new tires being manufactured for the larger 5th wheel trailers. Of course many of them are ST. Some manufacturers have the ST235/85R16F rated at 3960# @ 95 psi. Others have newer ST tires sized ST235/85R16G rated at 4050# @ 110 psi.

The 129 you seek may be found on LT & ST tire sidewalls as it's allowed to be there but it's not the official load measure of those tires. The load range letter is.

An example of the disparity between the two systems of load capacity measurements follows; LT235/85R16 - 120 = 3086# of load capacity at 80 psi. LT235/85R16E = 3042# of load capacity at 80 psi.
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Old 08-31-2015, 03:57 PM   #3
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Thank you Airdale

I've researched this extensively today and it seems I cannot get 4K tires on a 16" rim.

The best I can find are Goodyear G614 235/85/16 Tires with a load of 3750 which would be OK for my present weight.

I've called the RV dealer to ensure the Cardinal 3875FB model rims can support those tires.

Did I miss anything, or is the conclusion sound about the switch?

Thanks
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Old 08-31-2015, 05:18 PM   #4
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Quote:
Originally Posted by Shayne View Post
The best I can find are Goodyear G614 235/85/16 Tires with a load of 3750 which would be OK for my present weight.
IMO, on a 16" wheel- this is the highest that I know of.

That said, make sure you're not throwing good money after bad. I took a bath on a set of 4 Maxxis tires and 16" rims by upgrading to 17.5" tires.

The next thing you may want to check-out if you haven't already (I didn't read much of your "beefed up the camper posts).. running that heavy, your springs likely aren't prepared for it. I know once I started running heavier (and well before maximum capacity on the axles), my springs flattened out. I just replaced them at the same time as my wheels.
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Old 08-31-2015, 05:37 PM   #5
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Thanks Ependydad

Yes, I considered springs and axles as well. Turns out my rig upon weigh in is bit lighter than I thought and the G614's will still give me wriggle room beyond the axle weight. Across 4 tires comparatively 3750-3420 = 330 x 4 tires = 1,320 pounds more. Doesn't sound like a lot and I am not intending increasing weight, only the spec and safety rating by moving to a G rated, 14 ply tire

It's my personal opinion that the E rated Goodyear Marathon ST 235/80/16 3420lb load tires are crap (excuse the expletive but it seems fitting)

We had a blowout with the temperature, speed and PSI all within range on a smooth interstate road, and having checked that I was within spec I conclude it was a tire failure. I had the same tire shred also within the last 60 days

I individually weighed each axle on a split weigh using 2 x cat scales yesterday and I'm under the MFG';s spec, but want to put a little more tire weight head room between my load and the tire.

For anyone else looking at the same, check the spec of the rim as well. I checked mine and they are Sendel Brand model t09BM and the mfg website says a spec of 110PSI and 3750lbs load.
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Old 08-31-2015, 06:25 PM   #6
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LT235/85R16 LRG 14 Ply Sailun S637 Radial Trailer Tire

Call and ask them about the specs. It's a new tire and on some sites it's listed under Sailun S811. Other sites are confused about the ST. I've seen pictures of the new tire and it clearly has 129/LRG right on the sidewall.
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Old 08-31-2015, 06:38 PM   #7
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Here are the specs on the 3960# load capacity tire I mentioned earlier. There are other manufacturers building it.

ST235/85R16 Carlisle Radial Trailer Tire LR F 3,960 lb Capacity
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Old 08-31-2015, 06:38 PM   #8
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Thanks Airdale

We just purchased 5 x Goodyear G614 RST, 235/85/16 tires. A friend has a business and gave them at cost, something shy of $300 each including the expensive OK taxes! So $1,500 invested in our future.

Have the local GY shop fitting and balancing tomorrow. He will also put brass high pressure valve stems in the wheels and we will put the existing wireless TPMS caps on to monitor temp and pressure.

I'm hoping our blowouts may be behind us for a while. We put a lot of faith in Goodyear to drop $1500 on the same brand after all the issues, but two things convinced us:

(1) Checking around about GY, they have a good reputation. They have a claims dept. which apparently considers and may pay for RV damage. Tire pics and analysis and al the paperwork required, and when I rang today they were closed, but will start that tomorrow, so we will see

(2) My belief that the MFG of the rig used the absolute minimum spec they could. The rims can handle 110 PSI at 3750 lbs load, so why not match the tire I just purchased? One of the most critical safety aspects of a rig and in my view an important one not to scrimp on.

Lastly, it's amazing to me asking around the RV Park how many have no idea of how much axle weight they have ot total rig weight. The they pull with a lighter truck at high speed and wonder what happened!

Safety first!
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Old 09-07-2015, 09:04 PM   #9
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Thanks Airdale

snip

Lastly, it's amazing to me asking around the RV Park how many have no idea of how much axle weight they have ot total rig weight. The they pull with a lighter truck at high speed and wonder what happened!

Safety first!
Not surprised about people not knowing the weight. Probably one of the reasons that over half of RVs have one or more tire & or axle in an overload condition when individual tire scales are used. With this high a % is it any wonder why so many RV tires fail?
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