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Old 03-11-2020, 10:21 AM   #1
Montana Man
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M.O.C. #21963
Sailun 80 vs. 85 size

Because of you folks, (in a good way) I chose Sailun for our replacement tires. I have the GYs and had no issues. I did however go with the 80 series opposed to the 85. According to specs the 80 is closer in height and has a higher load rating than the GYs. I would have went with the 85s but they are an inch (half inch actual) taller.

I raised the trailer 1 1/2" with blocks to ride with the truck. That has proven to be a good move. Had I bought the 85s first I could have gotten away with 1" blocks, doh!

Any thoughts on this?
 
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Old 03-11-2020, 11:17 AM   #2
Carl n Susan
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I went with the 85 series and there is plenty of room for them.
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Old 03-11-2020, 11:42 AM   #3
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Seems to me 6 of one, half dozen of the other. I assume you went with "G" rated tires? As long as you're towing level, or close to it, then it seems like a wash.

I'm currently just shy of level and plan to move to the 85's when I buy new tires.
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Old 03-11-2020, 01:31 PM   #4
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I had already bought a new set of wheels at the rally last year to put on our unit, but with all of the discussion of it going back to the factory I never did. The ones I bought are rated at #4400 each and we were going to put the 85 series Sailuns on them. Now, we'll have to wait and see as it's at the factory.
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Old 03-11-2020, 03:00 PM   #5
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Quote:
Originally Posted by jsb5717 View Post
Seems to me 6 of one, half dozen of the other. I assume you went with "G" rated tires? As long as you're towing level, or close to it, then it seems like a wash.

I'm currently just shy of level and plan to move to the 85's when I buy new tires.
We have a similar setup. Depending on your current tires, the 85s may raise the rear a bit. With my trailer 1 1/2" at the axles raised the rear 2 1/4" which was perfect. These Rams sure ride high for towing fivers.
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Old 03-11-2020, 03:29 PM   #6
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Some people who are really height conscious, will go with the 17.5" wheels along with Sailun 215/75/17.5 as this combo is nearly identical to the 80 series tires with much more capacity.
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Old 03-12-2020, 04:30 PM   #7
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I’m getting a lot of flack with my tire posts lately so I’m going to set the stage.

My comments here are Pros & Cons and will fall in-line with tire rules & regulations and tire industry standards. In other words, I’m not going to step over the safety line.

First off there is the question of who to seek information from when changing tire designated sizes. It’s always the vehicle manufacturer first. The following quote is from the Keystone generic 2020 owner manual.

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information.”



A tire’s designation is a primary factor in the tire size. ST235/80R16 is a designated size. ST235/85R16 is a designated size. Because they use different load inflation charts they are not interchangeable without vehicle manufacturer approval. That approval can be predetermined when offered as a vehicle manufacturer option.

Replacement tires all fall under the same basic industry standard which says, in part, that they must provide a load capacity equal to or greater than the OE tires provided. All new – post 2007 – standards will also mention that they must be of the same designated size. ST235/80R16 a designated size with four load range numbers, D – E – F & G. Speed ratings are provided by individual brand builders.

When going up in load range, wheels & valve stems must have the ability to support the increase in Load, PSI or Both.

Keystone has always built most of their trailers with very close axle spacing. Some are so close they will not allow even the slightest increase in tire overall diameter.

When a consumer goes out on a limb and arbitrarily uses unauthorized replacements, they should know the proper procedures to follow. (The procedure is the same for authorized or unauthorized plus sized tires.) NHTSA allows auxiliary tire placards when plus sized tires do not meet the standards of a load inflation chart for the OE tires. The auxiliary placard should list the new tire size and the cold inflation pressure needed for them to provide a load capacity at least equal to the load capacity the OE tires provided. The proper location for the auxiliary placard is adjacent to the original.

Example of an auxiliary tire placard. Trailer or Light Truck tires would have load range in place of load index.

Click image for larger version

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Old 03-12-2020, 05:36 PM   #8
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On our 2012 3402RL, it was delivered with the ST 235/80R16 load range E Marathons. After going through five of them due to various failures in less than one year we upgraded to the Goodyear G614's. This worked, as the G614's were an option from the factory, using the same wheels that the rig came with, and with the addition of metal valve stems, the tires were the answer for the tire failures with the E range Chinese tires. There is plenty of space between the tires, so this was never a question, and I'm pretty sure most Montana's come with axles spaced far enough apart to not be a problem using either the 80 series or the 85 series tires.
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Old 03-12-2020, 08:09 PM   #9
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I also was thinking to upsize when replacing tires. Noticed that the Sailun 17.5 come in different rim width 6" & 6.75" vs the standard 16" that are on the rig now (6.5"). Does that make any difference? I also see a reference to offset????
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Old 03-12-2020, 08:15 PM   #10
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Quote:
Originally Posted by CalandLinda View Post
I’m getting a lot of flack with my tire posts lately so I’m going to set the stage.

My comments here are Pros & Cons and will fall in-line with tire rules & regulations and tire industry standards. In other words, I’m not going to step over the safety line.

First off there is the question of who to seek information from when changing tire designated sizes. It’s always the vehicle manufacturer first. The following quote is from the Keystone generic 2020 owner manual.

“To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information.”



A tire’s designation is a primary factor in the tire size. ST235/80R16 is a designated size. ST235/85R16 is a designated size. Because they use different load inflation charts they are not interchangeable without vehicle manufacturer approval. That approval can be predetermined when offered as a vehicle manufacturer option.

Replacement tires all fall under the same basic industry standard which says, in part, that they must provide a load capacity equal to or greater than the OE tires provided. All new – post 2007 – standards will also mention that they must be of the same designated size. ST235/80R16 a designated size with four load range numbers, D – E – F & G. Speed ratings are provided by individual brand builders.

When going up in load range, wheels & valve stems must have the ability to support the increase in Load, PSI or Both.

Keystone has always built most of their trailers with very close axle spacing. Some are so close they will not allow even the slightest increase in tire overall diameter.

When a consumer goes out on a limb and arbitrarily uses unauthorized replacements, they should know the proper procedures to follow. (The procedure is the same for authorized or unauthorized plus sized tires.) NHTSA allows auxiliary tire placards when plus sized tires do not meet the standards of a load inflation chart for the OE tires. The auxiliary placard should list the new tire size and the cold inflation pressure needed for them to provide a load capacity at least equal to the load capacity the OE tires provided. The proper location for the auxiliary placard is adjacent to the original.

Example of an auxiliary tire placard. Trailer or Light Truck tires would have load range in place of load index.

Attachment 5778
The supplemental tire sticker is interesting. In my case, the 80 series tire is very similar in size to the original GY 85 series but with a much higher load rating. The 85 series Sailun is physically different than the original GY of the same advertised size. Manufacturers do tend to do what they want with sizing even when sizing should be standardized.

The lesson I learned is to check the manufacturers actual stated size and load rating when comparing brands.
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Old 03-13-2020, 03:13 AM   #11
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Quote:
Originally Posted by Montana Man View Post
The 85 series Sailun is physically different than the original GY of the same advertised size. Manufacturers do tend to do what they want with sizing even when sizing should be standardized.
Goodyear's G614 is really a bastardized tire built under the design parameters of an LT tire but with special features that led to it being called an RST (Regional Service Trailer) and limited to that service. When using the designated size LT235/85R16 it must conform to the TRA standardization charts for LT tires which is 3750# of load capacity at 110 PSI for the LRG.

The designated size, ST235/85R16 uses the TRA standard for a Special Trailer Tires which is 4400# of load capacity at 110 PSI for LRG.

Just an, Oh by the way note: Under the new RVIA 10% load capacity reserve recommendation for RV trailer tires, the GY G614 no longer qualifies for service on vehicle certified 7000# axles.
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Old 03-13-2020, 04:58 AM   #12
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[QUOTE=CalandLinda;1176722
Just an, Oh by the way note: Under the new RVIA 10% load capacity reserve recommendation for RV trailer tires, the GY G614 no longer qualifies for service on vehicle certified 7000# axles.[/QUOTE]

EXACTLY!!! That is why tires like the 235/80/16 Sailun S637 with a rating of #4080 pounds has become the "standard" for 7k axles.
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Old 03-13-2020, 06:33 AM   #13
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Axle spacing has been brought up in this and other threads as one of the ways to determine if you can use an 85 series tire. In round numbers, you are talking about a tire that is 1 inch larger in diameter vs the 80 series or put another way. 1/2" on theradius dimension PER TIRE or 1" closer together for the two tires. Looking at our HC with 33" axle spacing (some are 35"), and currently with LT 31.7" diameter85 series tires, there is still approximately 3 inches clearance.

From Sailun's site:

5540993* ST235/85R16 132/127 L 14 12 6.50 31.7 9.3 14.7 4400 3860 110
5541960* ST235/80R16 129/125 L 14 10 6.50 30.8 9.3 14.7 4080 3640 110
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Old 03-13-2020, 11:10 AM   #14
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That's good info, thx all! Sounds like the GYs will be phasing out from the new heavy rigs. Had I not already raised the trailer I probably would have went with the 85s in spite of slightly lowered rolling and braking efficiencies.
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Old 03-13-2020, 11:41 AM   #15
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A point to remember when changing sizes from a designated ST235/80R16 to a designated ST235/85R16 is such a change is considered going to a "plus sized" tire. The tire inflation pressures and tire designated size will be invalid on trailer's certification label, in it's owner manual and on all other tire load placards.

Unless Keystone offered the "85s" as an option it's very doubtful they would approve the "85s" and tire safety wise the consumer would be out on their own limb - so to speak.
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Old 03-13-2020, 11:44 AM   #16
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Quote:
Originally Posted by CalandLinda View Post
A point to remember when changing sizes from a designated ST235/80R16 to a designated ST235/85R16 is such a change is considered going to a "plus sized" tire. The tire inflation pressures and tire designated size will be invalid on trailer's certification label, in it's owner manual and on all other tire load placards.

Unless Keystone offered the "85s" as an option it's very doubtful they would approve the "85s" and tire safety wise the consumer would be out on their own limb - so to speak.

Balony - again!!!!
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Old 03-13-2020, 02:13 PM   #17
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Balony - again!!!!
Where is your dissatisfaction?

This is a quote right out of the 2020 Keystone owner's manual.

"To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer."

That's a pretty straight forward quote. To top it off, ALL tire manufacturers will publish that same statement.
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Old 03-13-2020, 04:47 PM   #18
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Quote:
Originally Posted by CalandLinda View Post
Where is your dissatisfaction?

This is a quote right out of the 2020 Keystone owner's manual.

"To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size recommended by the manufacturer."

That's a pretty straight forward quote. To top it off, ALL tire manufacturers will publish that same statement.



That is CYA wording, same as virtually eveything else you purchase in today's marketplace and as set forth by a covey of lawyers.



Thor/Keystone/Montana or any other brand does NOT give a dang what tire you use once that ownership paperwork is signed and you haul that RV off the lot. The only worry I or any other RV owner has is to maintain the bare minimum weight carrying capacity as noted on the yellow sticker. If you upgrade in size or weight capacity, that is a benefit to an RV owner. All Thor/Keystone/Montana cares about is the bottom line on their profit/loss spread sheet and that they, the manufacturer use the absolute bare minimum costwise and (hoped for) safet wise. We can challenge them on some of the crap tire used but they purportedly are of the right size and the right capacity though owners have proven that as a falicy.


Why don't we discuss brakes and their lack of capacity to safely stop a 12.000-18,000 towed RV? To me that's a lot more important. The current Montana's have exactly the same brakes right down to part number as the 1976 5th wheel I owned and that 30 footer only weighed in at about 8000 pounds. Why isn't that covered by a CYA paragraph. Isn't changing to disc brakes a non-OEM mod that affects safety in a positive manner such as added capacity brakes? Sorry, your cut and paste argumebt fails.
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Old 03-13-2020, 06:20 PM   #19
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How do I determine the tire inflation psi I should be inflating any tire to.

Where do I go to get that info?
So many different theories on how much air to put into your tires but no "go to" reference so anybody can make the proper calculations if needed.

Or do I simply put the maximum PSI per the tire specs and deal with whatever "ride issues" come with that psi?

Tire newbs want to know.
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Old 03-13-2020, 11:43 PM   #20
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Originally Posted by BiggarView View Post
How do I determine the tire inflation psi I should be inflating any tire to.

Where do I go to get that info?
So many different theories on how much air to put into your tires but no "go to" reference so anybody can make the proper calculations if needed.

Or do I simply put the maximum PSI per the tire specs and deal with whatever "ride issues" come with that psi?

Tire newbs want to know.
The first, best place, to get information on your vehicles tire inflation pressures is in their owner's manual.

Here is a link to the 2019 Keystone owner manual. Proper tire inflation is on page #17.

https://www.keystonerv.com/media/914...anual-2019.pdf

Remember, only the vehicle manufacturer has the authority to set the recommended tire inflation pressures for Original Equipment tires. Optional inflation pressures are at the discretion of the vehicle owner and start at what has been recommended and stop at the maximum allowed on the tire sidewall for maximum load.

It is never recommended to use inflation pressures below vehicle manufacturer recommendations for any normal conditions.
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