Correct tire pressure

[Bruce0850]

I have Montana 3820FK with Sailun 637 tires. I know they are rated at 110 psi. What is the correct pressure for towing. I know they will heat up on hot days, and increase the pressure, so don't want to get over the max.
What does everyone run at, with these tires?

[rohrmann]

They are rated to be run at 110 psi COLD. That is the pressure after they have not run for at least three hours, or better yet, in the morning before you start driving. They will increase above 110 psi when rolling down the road, maybe even above 135 psi on a hot day, but the tire is designed to do that safely, so never run them so low that they have to run to get to 110 psi.

[The Bone]

I would check the wheels to make sure that they can handle that pressure. Mine are stamped for 80 but I think thats cold tire pressure and can handle more when the tires get hot.

[racquetballfreq]

I don't think you want to put 110 lb rated tires on 80 lb rated rims. I'm sure others will chime in here and confirm this.

[mlh]

As the pressure decreases so does the load ratings. There is no reason to run them at anything other than max pressure.
Lynwood

[Dusters]

The S637 ST Metric Chart shows various PSI for load specification. The chart was posted in a previous post relating to Sailuns S637. The tire installer checked his specifications and said they would inflate the tires to approximately 95 to 100 PSI for single axle usage of over the 3420 (80 PSI @ 3420) on the ST235/80R16. If the Max load is 4080 and our load is approx. 400lbs less, would it not make sense to run slightly less than max psi?

[Beau2010]

Our Sailuns are set at 110 psi cold. On a hot day, they will get up to near 130 psi but rarely are warmer than about 10-15 degrees above the ambient temp. On cold days, they won't get much above 115 psi.

[BB_TX]

You need to look to see if Sailun has a inflation/load chart. Some manufacturers say inflate to max sidewall pressure. Some say inflate according to the actual weight on the tire up to the maximum sidewall pressure.

Tires inflated to a pressure much greater than needed to carry the actual load tend to wear more in the center than at the edges since the tire tends to balloon out. And will ride harsher. Tires inflated lower than the pressure needed to carry the actual load tend to wear more on the edges than at the center. And if underinflated too much will also run hotter. The idea of inflating according to the actual load is to keep the tread to ground contact as flat as possible to maximize contact surface area, evening out the wear pattern. At the same time the maximum contact area also maximizes traction for stopping.

If there is no inflation/load chart available, or if you do not know the actual weight on the tires, it is better to inflate toward the maximum sidewall pressure than risk underinflating.

[Mark N.]

Everyone needs to remember to set tire pressures "cold". DO NOT try to compensate for the normal rise in temperatures that driving causes and DO NOT try to compensate for ambient outside temperatures. Also, "Cold" means you haven't driven on them! It has nothing to do with ambient temperatures. For instance, I set a cold tire pressure in northern Utah in Jan. where the outside temps. are 12 degrees to 105 lbs. I then set the same 105 lbs. cold pressure in Phoenix when it is 105 degrees outside. Same "cold" pressure setting, but vastly different ambient temperatures outside. This is a very common mistake people make.

[phillyg]

MarkN is absolutely correct. Has anyone found a load/psi schedule for the Sailun G637?

[WeBeFulltime]

I would check the wheels to make sure that they can handle that pressure. Mine are stamped for 80 but I think thats cold tire pressure and can handle more when the tires get hot.

There is no way that Keystone would put 80psi wheels on a 3820FK! :confused:

[Charli]

"Cold" Means not having been driven recently and also means not having sat in the sun. I've had situations when the tires in the sun have been 5 PSI more than on the shady side of the truck/trailer. Guess I have to get up earlier.

[baybum10]

Attached is chart provided by Sailun customer service.

[rohrmann]

The chart is good, and if only you are running the 85 series Sailuns, you can get by with only inflating them to 80 to 95 psi, but if you are running the 80 series, it's 110 psi, or you are capable of no more than an E rated tire. With either tire, and also the G614 and probably the other G rated tires, the ride and handling will be greatly improved by running at 110 psi, and the tires will run cooler as an additional benefit. The axles on these rigs needing the heavier tires are rated at 7,000 lbs, so the tires need to be at least capable of 3,500 lbs, and higher will provide a better safety margin, and improved fuel mileage.

[phillyg]

Attached is chart provided by Sailun customer service.

Thank you baybum10.

[BB_TX]

I am going to disagree about ride and handling being better at 110 psi. The higher the pressure the "harder" the tire will be. Unless the actual weight on the tire requires that pressure, the ride will be harsher and the traction will be lower. That is why tire manufacturers publish a weight to inflation table for their tires.

Tires inflated in excess of that required to carry the actual load on those tires will tend to balloon out and support more of that weight on the center area of the tread rather than being distributed more equally across the tread. That will result in a harder ride, lower traction, and more wear in the center.

I do agree about better fuel economy and probably somewhat lower temps.

Disclaimer: I am not a tire expert but there is adequate info on the internet from reliable sources to back that up. And if it is on the internet it must be true. :D

[dfryk]

I am going to disagree about ride and handling being better at 110 psi. The higher the pressure the "harder" the tire will be. Unless the actual weight on the tire requires that pressure, the ride will be harsher and the traction will be lower. That is why tire manufacturers publish a weight to inflation table for their tires.

Tires inflated in excess of that required to carry the actual load on those tires will tend to balloon out and support more of that weight on the center area of the tread rather than being distributed more equally across the tread. That will result in a harder ride, lower traction, and more wear in the center.

I do agree about better fuel economy and probably somewhat lower temps.

Disclaimer: I am not a tire expert but there is adequate info on the internet from reliable sources to back that up. And if it is on the internet it must be true. :D

A good friend is also a big tire supplier to a lot of farmers and RV folks here in the area. He also owns a 5h wheel. He strongly suggests running G rated tires at 110 pounds COLD regardless of weight. A decent quality G rated tire will not balloon. That is why the have the extra cords inside so they can handle the weight at max pressure.

[Pocketlake1]

I see the consensus is to inflate tires to the maximum rating for a particular tire, ex 80psi. I have always been reluctant to "max" out anything so have been running my tires on truck and rig at 75psi, the max rating for both being 80. I get the impression it makes almost no difference between 75 and 80 psi, other than perhaps a little stiffer ride at 80? I pretty much only run 60-65mph on the highways when hauling our rig. I am the tortoise and get passed by everyone

[Dusters]

Pocket: You mention your truck tires above and I run my truck tires at the standard recommendations. With extra weight on the rear, they inflate another 10 psi anyways. As mentioned above, the tire brands have recommended axle weight charts and even though my FW is a tad lower weight than the 110 PSI column on the brand chart, I feel 100 to 105 PSI is adequate. That last 10 PSI for some compressors is a stretch at times.

[Trailer Trash 2]

Low tire pressure on your RV will cause Higher tire temperatures and that is not GOOD. I'm not looking for a comfortable ride for my trailer, I have 4 shock absorbers on my axels to take care of the road jarring, my Montana tracks very good with the manufactures suggested tire pressure, I maintain the air pressure every time we go on a trip. the other is I don't buy Good Year tires for my Montana, I buy LT tires that's what it came with from the factory.

[JABURKHOLDER]

On my dually I run 80psi on the front and 75psi on the back.
On my rig (614's) I run 100psi. For my weight, I don't need more.


Concur with BB TX, higher psi than needed creates a harsher ride and creates less tire footprint on the road.


Just because your tires and rims say max 110psi doesn't mean your rig needs max.


That being said, better to error on the high end. The low end will give you a LOT more problems. JMHO

[Texan]

I have the Sailuns and my 3402 rl weighs 16,200 lbs loaded and i run mine at 110 psi.I have over 12,000 miles on the tires and they look to be wearing evenly. I do have the independent suspension but i would be more worried about tire heat build up than the ride. Having more tire to pavement contact sounds good but when you are turning, the less contact is better than more. There is a lot of stress on the tires and suspension when making sharp turns going forward or backwards.As for as wearing out your tires prematurely with more air, you will most likely have your tires time-out before they wear-out.More air means more safety margin when dealing with load capacity and these Montana's are pretty heavy. Why have a G rated tire if you are not going to take advantage of the increased load capacity.

[mlh]

Well said Texan especially the last sentence.
Lynwood

[Ram Montana High Country]

OK - lots of good input - my question is: NITROGEN fill - my Uncle has a bed camper, adds 3000 LBS to truck. His comment was, "Without Nitrogen, he'd pull into rest area and could not put his had on the tires comfortably. With Nitrogen he could"
Worth the money?

[mlh]

Worth the money? No.
Air is about 78% and that's good enough for me.
Lynwood

[phillyg]

Texan said, "Why have a G rated tire if you are not going to take advantage of the increased load capacity."

For the first time that I know of, we have a published psi chart for an ST tire. Perhaps that's because the Sailun G637 is a rebadged all position LT tire.

Previously we were well-advised to run cruddy ST tires at max psi because anything less could cause overheating and blowouts. Now, those FWs between 13-16,000lbs with G-rated Sailuns can be run at less than 110psi.

My FW is probably near the top end weightwise, so I'm starting at 110psi and I've not noticed any difference in ride. I need to get weighed and I'm going to moniter tread depth. If greater in the middle I'll start going down in psi, but no lower than the chart spec.

[phillyg]

OK - lots of good input - my question is: NITROGEN fill - my Uncle has a bed camper, adds 3000 LBS to truck. His comment was, "Without Nitrogen, he'd pull into rest area and could not put his had on the tires comfortably. With Nitrogen he could"
Worth the money?

I'm thinking it's more likely his truck was overloaded with the camper, and without using a temperature gauge, it's difficult to know the real temp. Air is 78% nitrogen and I believe it's only recommended as a marketing ploy.

[Texan]

Weighing your rig will cut out the guessing.I've never heard anyone have problem with there tires running maxium pressure but running low can and will create build-up of heat which is poison to your tires. If a person never wears out there tires then it would probably be wise to keep the maxium pressure for the cooler running and i believe it would more than compensate for the rougher ride. I put about 5 to 6 thousand miles a year on my rig so my tires will most likely time out before they wear out. As hard as the rubber is on the sailuns i could easily see someone getting 40 to 50 thousand miles on there tires if they don't time-out first. ' COOL IS BETTER' especially in the summer.

[CaptnJohn]

Here is the email I received from Sailun today. I plan to run them at 100PSI.




John, thank you for being a Sailun customer. Inregards to your inquiry, I am assuming the weight you provided was fully loadedand that you have two axles (4 tires).


The math works out to 3500 lbs./tire. I have attachedthe load and inflation table for ST tires. You will see that at 80 psi,the tire will carry 3640 lbs./tire. So, you can go as low as 80psi. If you want to build some safety in, you can run your tires at 85 or90 psi. The issue with putting too much air is you will find your trailermay “bounce” a little going down the road. You may have to experiment alittle to find the optimal pressure.





You will see the chart only shows up to a 10 ply (“E”) ratedtire. For each 5 psi increase in air pressure, you can carry anadditional 120 lbs. of weight/tire. up to 110 psi.





Hope this helps. Safe travels.





Al Eagleson‘ACE’


Director, Commercial TruckProducts

[rohrmann]

Phillyg, I think you are mistaken about the Sailun tires, actually S637. If you look at the product sheet, the two 16" sizes have a little '*' next to the part code, and the note indicates that, "All steel construction specifically designed for Trailer application only. Requires special high load capacity wheel. Consult wheel manufacturer for proper application", so these tires, just like the Goodyear G614, are only to be used for trailer applications

http://www.sailuntires.ca/MRT/S637.html

These tires were always intended to be used as a trailer tire, never were all position.

[phillyg]

Phillyg, I think you are mistaken about the Sailun tires, actually S637. If you look at the product sheet...... these tires, just like the Goodyear G614, are only to be used for trailer applications......
http://www.sailuntires.ca/MRT/S637.html

Yep, typo or brainfart about the "S" v. "G." OTOH, I had to go back in time about the Sailuns only being used for trailer applications, and could not find the specific reference I was looking for. It was a govt. document about some Chinese mfgrs. "rebranding" tires to get around the 2009 Obama administration decision to put a 35% import tariff on passenger and light truck tires.

There was some action in 2014 from US interests to exclude ST tires from the tariff (even though it was unclear to me that the 2009 tariffs ever involved ST tires). I think, but can't now disprove the asterisk in the Sailun product sheet. So, good catch on the asterisk.:)

[rohrmann]

The change from the Sailun's being LT tires to what they are now, ST, is the reason you mentioned, to dodge the import tariff on the tire being classed an LT. Still, when they were rated an LT tire, just like the Goodyear G614, which is still rated an LT tire, they both were always spec'd to be a trailer tire only.