Recommended tire pressure

[Paul & Deb]

And the truth will set you free! Thank you!

Here's the spreadsheet he sent me.

[Cate&Rob]

So, I am going to send him a follow up email with a couple more questions I have but in the mean time I am dropping my air pressure to the trailer label pressure of 80 psi.

Hi Paul,

This fits with what is learned by those who make the same inquiry of other tire manufacturers. But . . . remember that the weight of your 337 is not divided equally amongst the four tires. The tires on the left side are each carrying about 500 lbs more than the tires on the right side. I would think that your plan to run 80 psi would cover this weight difference.

"the tire is engineered for this pressure for the load" directly from Sailun, is the same message from all tire manufacturers for their tires.

Rob

[MidwestCamper]

When we head south in the winter, the temps are usually 50 degrees colder than where we arrive at our destination later that same day (and 4,000' lower). That's why the "cold" temp phrase always seemed ambiguous to me. What I've learned is the increase in pressure while driving is far higher than the ambient temp psi differences when "cold".

Brian,
Good observation. In this special case, you could monitor your running pressures with TPMS to be sure you are not dropping pressure below your recommended cold settings, which is unlikely. As Rob has stated, you have two competing actions with tire pressure and temperature rising initially while your ambient temperatures are falling. It would not be a straight forward relationship since your tires will maintain some level of elevated temperature and pressure while towing due to friction, heat from braking, etc. This is why its important to inflate at cold temperatures or you would be chasing this almost endlessly due to changing conditions. Once you arrive at the colder conditions and have soaked overnight, your cold pressure would need to be adjusted.

[howson]

HOWEVER .... I recently put Sailuns on my 337

Paul,
By no means am I intending this as adversarial so please do not misunderstand my intent. That intent is to ensure someone who reads the post understands the full scenario.

What must be understood by those reading your comments is there are Load Range G (in the case of Sailun 4,080 lbs @ 110psi) tires on a trailer spec'd for Load Range E (3,520lbs per tire @80 psi). For the majority of owners that have the OEM spec'd tires, setting the air pressure to the label on the trailer (usually the max of the tire) is still the correct advice. Gary, the OP, I assume has a Momentum since he posted here--a heavy trailer on a good day. Much, much heavier than your 337 or my 315. The last thing (IMHO) Gary should do is lower air pressure which lowers the load carrying capacity of his unit.

If I'm reading the excel spreadsheet (a few posts down) correctly, the Sailun has a rating of 3420lbs @ 80psi. Again, no contention meant in this question, but what's the point of Load Range G tires if they are deflated to the Load Range E capacity?

I hope that gentlemen who asked about air pressure while at the dealer sees this post. After recommending 110psi in his Sailuns I found it was on a trailer spec'd for the E's. I have regretted that post and have asked him multiple times to follow up with Sailun because based on what I know now I agree the 80 psi is correct in this situation.

-Howard

[MidwestCamper]

Paul,
By no means am I intending this as adversarial so please do not misunderstand my intent. That intent is to ensure someone who reads the post understands the full scenario.

What must be understood by those reading your comments is there are Load Range G (in the case of Sailun 4,080 lbs @ 110psi) tires on a trailer spec'd for Load Range E (3,520lbs per tire @80 psi). For the majority of owners that have the OEM spec'd tires, setting the air pressure to the label on the trailer (usually the max of the tire) is still the correct advice. Gary, the OP, I assume has a Momentum since he posted here--a heavy trailer on a good day. Much, much heavier than your 337 or my 315. The last thing (IMHO) Gary should do is lower air pressure which lowers the load carrying capacity of his unit.

If I'm reading the excel spreadsheet (a few posts down) correctly, the Sailun has a rating of 3420lbs @ 80psi. Again, no contention meant in this question, but what's the point of Load Range G tires if they are deflated to the Load Range E capacity?

I hope that gentlemen who asked about air pressure while at the dealer sees this post. After recommending 110psi in his Sailuns I found it was on a trailer spec'd for the E's. I have regretted that post and have asked him multiple times to follow up with Sailun because based on what I know now I agree the 80 psi is correct in this situation.

-Howard

Howard,
Its also important to note that some (like myself) feel better to have an over spec tire but will air it based on the load capacity. If someone makes this choice and airs the higher rated tire to max sidewall pressure, they will add undue stress to the axles, hangers, suspension and more. To move to the higher rated tire and air based on the charts adds the confidence in a heavier constructed tire that is not running at its max capacity.
The originally factory installed tires or replacements of the same load capacity should always be aired to the pressure listed on the yellow tag supplied by GDRV.

[howson]

Howard,
Its also important to note that some (like myself) feel better to have an over spec tire but will air it based on the load capacity. If someone makes this choice and airs the higher rated tire to max sidewall pressure, they will add undue stress to the axles, hangers, suspension and more. To move to the higher rated tire and air based on the charts adds the confidence in a heavier constructed tire that is not running at its max capacity.
The originally factory installed tires or replacements of the same load capacity should always be aired to the pressure listed on the yellow tag supplied by GDRV.

Well written, Jim. I agree completely.

I've learned a LOT about tires on this forum.

[John303]

This topic is a favorite as folks come into RVing, and have to sort through various scenarios and opinions. I think the sanest advice is this link, especially the last paragraph dealing with RVs. One thing to keep in mind is that as RVs travel down the road, the side loading from wind and truck traffic place additional load on the tires, hence inflating 10-15 lbs over what the inflation chart states is appropriate, not exceeding maximum of course. Like medicine, if some is good, more must be better is not true, as the article brings out.

https://rvsafety.com/articles/writte...-tire-pressure

[ElSimon]

This has been an interesting read.

I had an interesting thought this morning. I have a 330GK, 5th. Rough dry weight is 12,200 lbs. It is currently parked next to my house waiting patiently for us to take it South (Zion Nat'l Park) for Thanksgiving. It is sitting on its 4 wheels with the 6 auto leveling stabilizers down and NOT hitched to the truck. With a good portion of the weight sitting on the stabilizers would I get an accurate read on my tire pressures? I would rather have them inflated to the driving pressure while I am parked and loading up instead of waiting until I am hitched and wanting (needing) to get on the road and having to fill them up at that time. Will the difference of lower load (via the stabilizers) be enough of a difference to worry about? I saw one website that indicated the difference for trailers in general might only be 1 psi. I found that hard to believe. Even if the stabilizers take 1/2 of the load that is still a 6,000+ change in the load on the tires. There will also be 1,200 lbs pin weight off the tires when I am hitched.

I am an engineer by trade and DNA so I tend to over annalize these things.

[CoChris]

This has been an interesting read.

I had an interesting thought this morning. I have a 330GK, 5th. Rough dry weight is 12,200 lbs. It is currently parked next to my house waiting patiently for us to take it South (Zion Nat'l Park) for Thanksgiving. It is sitting on its 4 wheels with the 6 auto leveling stabilizers down and NOT hitched to the truck. With a good portion of the weight sitting on the stabilizers would I get an accurate read on my tire pressures? I would rather have them inflated to the driving pressure while I am parked and loading up instead of waiting until I am hitched and wanting (needing) to get on the road and having to fill them up at that time. Will the difference of lower load (via the stabilizers) be enough of a difference to worry about? I saw one website that indicated the difference for trailers in general might only be 1 psi. I found that hard to believe. Even if the stabilizers take 1/2 of the load that is still a 6,000+ change in the load on the tires. There will also be 1,200 lbs pin weight off the tires when I am hitched.

I am an engineer by trade and DNA so I tend to over annalize these things.

In theory yes, the tire pressure should increase as you increase the load (the tire is an air spring). In practice, there is no SIGNIFICANT difference that I have seen between loaded and unloaded pressure. You will see a significant increase/decrease in pressure with temperature. Air temp will effect the cold tire pressure, but this is most noticeable when you start traveling traveling. On my Solitude 310GK, starting at 110 PSI cold I have seen a 20+PSI (over 130 PSI observed) after driving multiple hours on the freeway.

Chris

PS With the weight of a Solitude, I hope you have Load range G tires. If not, I would suggest upgrading. Grand Design used to ship the Solitudes (and Momentums) with load range E tires and there have been a number of tire failures. GD has switched (in 2018?) to load range G tires on Solitude & Momentum trailers and there have been fewer problems. Even with LRG tires, I would recommend replacing tires every 3 to 5 years. These tires are fairly heavily stressed and can see a lot of deterioration from weather. Tire failures (tread separation, blow outs, etc.) are no fun and can be quite costly in trailer damage.

Getting off my soap box now.