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Old 08-31-2022, 04:48 PM   #1
Joint Venture II
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Sailun S637T cold tire pressures

Since blowing out a tire in Washington and purchasing 4 new Sailun S637T ST235/85R16 G/14PLY Tires and having the dealer set the pressures @ 90PSI I've been watching tire temps and air pressures on my TPMS monitor. Generally temps are 102-112 on hot 80-90* days. Pressures increase to around 100-105 and tire wear after 2k miles seems to be good on all 4 tires with maybe a sign of the shoulders being more worn then the tire centers indicating a possible under inflation. What are your thoughts? Increase tire pressure or leave it alone?
 
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Old 08-31-2022, 05:24 PM   #2
Carl n Susan
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Given the light weight of your 2955RL, I believe your current pressure setting is appropriate. I think your ride will suffer if the tires are inflated to their max. cold pressure of 110 P.S.I.

The shoulder wear is normal. Both the Sailun and the GY G614 have extra rubber on the shoulder as the tire scrub inherent in any turn is hard on them.
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Old 08-31-2022, 05:52 PM   #3
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Given the light weight of your 2955RL, I believe your current pressure setting is appropriate. I think your ride will suffer if the tires are inflated to their max. cold pressure of 110 P.S.I.

The shoulder wear is normal. Both the Sailun and the GY G614 have extra rubber on the shoulder as the tire scrub inherent in any turn is hard on them.
Thank you, I will leave pressure cold at 90 PSI and I find the trailer does ride well at that setting too. Never thought of our 2955RL as a "light weight" but I'm sure it's all relative.
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Old 08-31-2022, 06:17 PM   #4
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"Light weight" is not a pejorative but merely amplifies the difference between it (at 12K GVWR) and current "heavy weight" (or pudgy, plump, chubby, zaftig, etc.) current Montanas (at 16.5K GVWR)
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Old 09-03-2022, 03:16 PM   #5
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For the 3121RL at the heavy weight of 16.5k, would the recommended 110 PSI be appropriate? That’s what I’ve been running mine at.
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Old 09-03-2022, 04:26 PM   #6
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Inflate your tires to the cold tire set pressure stated on your tires.........if that is 110 psi per these specs https://sailuntire.ca/en/plt/tires/S637st/ , that inflate them to that pressure. That is the same pressure I inflate my Sailun ST235/80R16G tires to.
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Old 09-04-2022, 08:46 AM   #7
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Inflate your tires to the cold tire set pressure stated on your tires.........if that is 110 psi per these specs https://sailuntire.ca/en/plt/tires/S637st/ , that inflate them to that pressure. That is the same pressure I inflate my Sailun ST235/80R16G tires to.
I disagree, there is a reason for weight charts . I was actually sent one by a Sailun rep. I run mine at 100 psi, and I could run them lower according to my weight .
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Old 09-04-2022, 09:37 AM   #8
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Only way to properly determine psi is weigh the rig, and use the Sailun load chart. While it's true that you can just use the 110 max psi embossed on the tire, there's no need unless you're at max load on the tires, which I doubt. And yes, psi and temps will increase as the tire rolls.
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Old 09-04-2022, 01:05 PM   #9
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Sailun tire inflation / load chart attached. Another consideration is inflating the tires to a psi that provides a safe load margin below the tire load limit. In my case, if inflated to 100 psi they would not offer adequate safety margin.
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Old 09-04-2022, 09:14 PM   #10
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I agree with using an inflation / load chart for my motorhome but always with a safety margin. In that case, they are inflated to 82 psi vs. 110 psi max cold tire pressure.
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Old 09-07-2022, 01:38 PM   #11
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Cold tire pressure is what the pressure indicates on the side of the tire. That pressure is set at the beginning of the travel day. I have talked to the tire manufactures engineer's and have been told the tire is designed to handle pressures that increase due to heat over the course of the day. They said tires are more likely damaged due to under inflation. If I remember right my Sailun tires are all steel so there are steel belts in the sidewalls. If those tires are not inflated properly they may see more damage due to under inflation! My suggestion would be to send an email to the manufacture of your concerns, most likely you will get a response from engineering. In the mean time I suggest you err on the safe side and don't under inflate your tires.
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Old 09-07-2022, 02:26 PM   #12
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I have 5 of the exact same tires, and my tire shop set mine at 100psi. They said 100psi gives room for expansion up to the 110psi max on the side without being too high and having expansion pressure above 110. A lot of people have said they do 110. I think some of it also depends on your rigs loaded weight, etc. I have been happy with 100psi so far so I’m sticking with it. We aren’t retired yet so I’m not towing thousands if miles like some on here are either..
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Old 09-07-2022, 02:49 PM   #13
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I have 5 of the exact same tires, and my tire shop set mine at 100psi. They said 100psi gives room for expansion up to the 110psi max on the side without being too high and having expansion pressure above 110. A lot of people have said they do 110. I think some of it also depends on your rigs loaded weight, etc. I have been happy with 100psi so far so I’m sticking with it. We aren’t retired yet so I’m not towing thousands if miles like some on here are either..
The max 110 pressure is for COLD tires, not hot. The tires will heat to well above 110 with NO issues. I run mine at 108-110 depending on how heavy I am. Problem with running low tire pressure than what is required is sidewall flex from under inflation. This will cause blow outs from weakening sidewalls from all the flexing. It also causes the tires to heat up more than normal. I have seen tire shops that never checked a load chart an just inflate to what they “think” the tires should be, and they were wrong. Like has been pointed out previously, there should be a safety margin in your psi of about 10%-15%. If you never weighed your rig and check the load chart you will not know for sure if your psi is correct. If you run your tires with a higher psi, they will wear better and roll better with lower temperatures because of less flex and friction.
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Old 09-07-2022, 02:56 PM   #14
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I also talked with Sailun when I bought the trailer. They said that I should keep them at the cold pressure on the side of the tire (110psi). I cant remember what he said they were tested to but it was surprising, I think some ware around 200psi. I just replaced all 4 because the dealer cut one during a repair. They replaced two and I replaced 2 since I had 30,000 miles on them as long as they could keep 2 of the 3 good ones (the third one is in my garage) as customer giveaways (I took that with a grain of salt) since they looked almost new with 30K on them.
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Old 09-07-2022, 03:03 PM   #15
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I contacted engineering because I was wondering what pressure I should start out in the morning. The manufactures engineer said some try to guess what pressure to start out at so the pressure would not increase over the pressure posted on the sidewall. He said that is a big mistake! He said to inflate the tires to the cold pressure level as indicated on the side of the tire at in the morning and that the tire manufacture have designed pressure and temperature increases into the tire. I chose not to listen to what I was hearing from the installer and went with what the manufacture was suggesting. I was also told that all steel radial tires will dissipate temperature increases better so I shouldn't see as great of a temperature pressure increase.
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Old 09-10-2022, 01:20 PM   #16
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I agree with you on tire pressure settings as that works for me on my 2955rl with the Sailuns.
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Old 09-18-2022, 08:44 PM   #17
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Is switching over to Sailun S637 ST/235 R16 14 ply best?
Reading all the comments about tires has gotten a bit confusing??? Will these be the right set for my Montana 2007 3500RL???
Totally confused about choices.
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Old 09-19-2022, 07:04 AM   #18
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Is switching over to Sailun S637 ST/235 R16 14 ply best?
Reading all the comments about tires has gotten a bit confusing??? Will these be the right set for my Montana 2007 3500RL???
Totally confused about choices.
How much does your loaded 3500RL weigh? If it's in the 14,000-16,000lb range, then yes, a good 14ply G-rated tire is required. With less weight, a good E or F-rated tire would suffice. OTOH, you could get a G-rated tire and use the mfgrs'. load table to adjust psi downwards to fit the load. If it hasn't been said enough, Sailuns are considered by most to be the best tire for heavy FWs.
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Old 09-19-2022, 12:35 PM   #19
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The PSI number on the tire sidewall IS NOT A RECOMMENDATION. It's the amount of cold inflation pressure for that tire to provide its maximum load capacity.

The OP has "plus sized" his tires to an extreme. The proper procedure for those replacement tires is to get a load inflation chart for them, find the vehicle manufacturer's recommendation for the OE tires and establish a new recommended cold inflation pressure that is equal to or greater than what the OE tires provided. Anything above it, all the way to tire sidewall max is considered optional.

https://fifthwheelst.com/documents/C...T-Modified.pdf
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Old 10-17-2022, 08:53 AM   #20
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good advice
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