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Old 12-26-2013, 07:20 AM   #1
Bander
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Join Date: Jul 2013
Location: Virginia
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Tire Upgrade Recommendations

I'd appreciate any recommendations or comments for tire/wheel upgrades on my 2012 Alpine 3600RS. I bought the coach used this summer. The original tires were Towmax STR Power King ST235/80R16. I have had two blow outs and one leak to flat in the last two months - three tires. I have read quite a few online posts regarding Towmax, blowouts, tires, coach weights, speed, etc. Although the Towmax are OEM I calculated that if the coach is at GVWR of 15,500 with a pin weight of 2240 then each wheel can take a load of 3,315 lbs. With Towmax's single max load of 3,520 @ 80 psi that is a 6% margin of safety. I've seen recommendations for margins of safety of 15-20% which means the tires need to have a max load capacity of 3,812 - 3,978.
To get higher load capacity I’m considering the following options:
- LT235/85R16 like Goodyear G614, LR G 3,750 @110 psi
- 10R17.5 like Michelin XZA, LR G 3,860 @85 psi – 4,805 @ 115psi, or
- 10R17.5 like Goodyear G114, LR H 4,675 @ 115 psi.
Keystone Customer Service won't give me a recommendation (probably for liability reasons) and referred me to their supplier Tredit Tire whom I will call.

I'm trying to get the coach weighed to see if that is an issue.

I'd appreciate anyone's comments.

Bander
2006 GMC 2500 Duramax
2012 Keystone Alpine 3600RS
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Old 12-26-2013, 08:18 AM   #2
Bluewater
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Don't forget to consider the load capacity of the wheels also.
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Old 12-26-2013, 10:30 AM   #3
KenBob
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We put 17.5 GY G114 tires on our Fuzion. The tires are load range H. However, the decision to use these tires were based on the tires overall strength of handling the issues of towing a large RV. Such as sharp turns in tight areas (tires don't roll, they slide especially on a triple axle), higher chances of hitting curbs in some situations, and the terrains they may encounter. Plus we have had bad experiences with the brand of tire that came on the Fuzion. The load carrying capacity is nice, but we have no reason to go over the capacity of the RV.
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Old 12-26-2013, 01:23 PM   #4
Agent 405
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I put 6 Gladiator 235/85 R16 ST tires on my Fuzion. They are 14 ply load range G tires rated for 3700 lbs each. I installed them last spring and have put about 2000 miles on them with no problems.
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Old 12-26-2013, 02:16 PM   #5
CWtheMan
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Quote:
Originally Posted by Bander View Post
I'd appreciate any recommendations or comments for tire/wheel upgrades on my 2012 Alpine 3600RS. I bought the coach used this summer. The original tires were Towmax STR Power King ST235/80R16. I have had two blow outs and one leak to flat in the last two months - three tires. I have read quite a few online posts regarding Towmax, blowouts, tires, coach weights, speed, etc. Although the Towmax are OEM I calculated that if the coach is at GVWR of 15,500 with a pin weight of 2240 then each wheel can take a load of 3,315 lbs. With Towmax's single max load of 3,520 @ 80 psi that is a 6% margin of safety. I've seen recommendations for margins of safety of 15-20% which means the tires need to have a max load capacity of 3,812 - 3,978.
To get higher load capacity I’m considering the following options:
- LT235/85R16 like Goodyear G614, LR G 3,750 @110 psi
- 10R17.5 like Michelin XZA, LR G 3,860 @85 psi – 4,805 @ 115psi, or
- 10R17.5 like Goodyear G114, LR H 4,675 @ 115 psi.
Keystone Customer Service won't give me a recommendation (probably for liability reasons) and referred me to their supplier Tredit Tire whom I will call.

I'm trying to get the coach weighed to see if that is an issue.

I'd appreciate anyone's comments.

Bander
2006 GMC 2500 Duramax
2012 Keystone Alpine 3600RS
I'll start off with the Keystone recommendation to see the tire retailer. That statement follows the "tire size" statement on page 18 of the generic keystone owner's manual found at the bottom of page 18. Keystone, in fairness to all other owners, cannot recommend replacement tires of any other size than what was used as Original Equipment (OE). In doing so they would open a can of worms - so to speak - that would cause them a great deal of problems with their in-house law advisors. However, if they had offered optional sized tires they could recommend their use without reprisals.

http://www.keystonerv.com/media/7289...al_4-25-13.pdf

There are not many options open to you if seeking replacements in 16" diameter sizes. I just happen to have a certification label from a Keystone RV trailer very close to your trailer's GVWR. Because Keystone fitted your trailer with ST235/80R16E tires rated at 3520# at 80 psi and did not notify NHTSA of their use on 7000# axles they had to derate your axles to a load capacity that would allow the use of 3420# capacity ST tires. There is a regulation about tires of the same design and size that require their load capacities to default to the lowest load capacity unless otherwise identified by letter to NHTSA defining their use. The ST235/80R16E has three distinct load capacities at 80 psi, 3420#, 3500# and 3520#. All default to 3420# unless otherwise noted on your trailer's certification label/Owner's manual.

http://www.irv2.com/photopost/showfull.php?photo=22027

Notice the rim size used on the certification label provided above. It's 16 x 6. It's the standard size used with that tire size. The LT235/85R16G requires a minimum tire width of 6.5". So even if you have the upgraded rims rated for 110 psi they are not suitable for the LRG tire. The specs for the GY G614 RST can be found in the following ref.

http://www.goodyearrvtires.com/tire-selector.aspx

Personally I think for long term use the 17.5" tires would be the most reliable fitment for your trailer. There are a wide range of brand manufacturers to select from. Many are mid level priced with very good reliability reviews. Fitment clearances can be easily duplicated to match those of your OE tires. I would avoid any with speed restrictions below 75 MPH and especially those below 65 MPH. The TRA doesn't allow tire pressure/load capacity manipulations for tires with manufacturer speed restrictions below 65 MPH. You can verify that by reading the Michelin tire data book.

CW
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Old 12-26-2013, 03:26 PM   #6
Bander
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Tire Upgrade Recommendations

Thanks for everyone's input - I appreciate the help.
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Old 12-27-2013, 08:54 AM   #7
jadatis
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I can explain it in a long article, but will keep it short.
ST tires are not that much different from LT , they are allowed about 15% more load then LT of same sises because of more deflection allowed for lower speed of 65m/h.

Tandem axle trailers can have large difference in load on the seperate wheels.
Often even crossed weightdifferences R/L between the axles.

That is reason why 6% reserve is to low.
You should do next sum in wich for tandem axle the maximum load for dual load has to be used wich is 7.5% lower then for single load.
This makes the calculation Max load LT = maxload ST/1.15*0,925= 80% to use from ST maxload for calculating advice pressure to give the tires same deflection an LT tire would have for dual load, and wich gives maximum life time and savety to the ST tire.
If you want to use the same sises and ST calculate with that or let me do it with my spreadsheet. If then pressure comes to 10 psi higher then that 80 psi wich is called the maxloadpressure, and is not the maximum pressure, it is allowed by TRA . So 90 psi would probably give your new tires with same sise ST the deflection that dont give damage to them in the long run, so no blowing tires anymore, but to be shure let me calculate it.
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