Recommended tire pressure

[MidwestCamper]

I always wondered what "cold" meant for tire pressures. Is 60 degrees cold? 20? I pumped my Sailun S637 tires to 106psi at 25 degrees thinking they would be at 110psi (at 60 degrees). I checked them the next morning at 55 degrees (in CA, not freezing cold central OR) and they were still 106psi! That surprised me.

What's even more surprising is these tires went to 124psi while driving at 60-70 degrees ambient. 20% jump in pressure!

Cold means at ambient temperatures just before travel where the tires are basically at the same temperature as their surroundings.

[bertschb]

Cold means at ambient temperatures just before travel where the tires are basically at the same temperature as their surroundings.

Right, but ambient could be -20 or 90.

[Cate&Rob]

Right, but ambient could be -20 or 90.

That is still the temperature at which you set your base “cold” tire pressures. Travelling from Canada to Florida, I have to reduce pressure every couple of days and going north I might have to add air.

Rob

[bertschb]

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".

[Cate&Rob]

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".

Hi Brian,

The change in elevation is working counter to the change in temperature. Pressures are set in psig (the g being gauge pressure relative to ambient pressure) As you go down in elevation the outside air pressure increases meaning that the psig of the tire will go down. At the same time, the ambient temperature is going up, meaning that the tire pressure is increasing. There was a time that I could have worked the PV=nRT equation https://en.wikipedia.org/wiki/Ideal_gas_law to give you the exact relationship . . . but that was a long time ago .

Rob

[D2Reid]

110psi, don't over think it.

[arhayes]

I always wondered what "cold" meant for tire pressures. Is 60 degrees cold? 20? I pumped my Sailun S637 tires to 106psi at 25 degrees thinking they would be at 110psi (at 60 degrees). I checked them the next morning at 55 degrees (in CA, not freezing cold central OR) and they were still 106psi! That surprised me.

What's even more surprising is these tires went to 124psi while driving at 60-70 degrees ambient. 20% jump in pressure!

My 17.5” 637’s take 125psi cold and it is not to usual to see 140+ psi once they are heated up rolling 60 mph.

[Paul & Deb]

Okay, so I have always gone with the crowd on "set them to the maximum cold pressure as listed on the tire" HOWEVER .... I recently put Sailuns on my 337 and, as we have discussed endlessly here, I aired them up to 110 per the tire sidewall but then I decided to send an email to Sailun customer support and check out their response!

Paul, thank you for your inquiry to Sailun Tire and for being a Sailun customer.

In regard to your question about inflation, I have attached the Tire and Rim Association load and inflation table for your size (reference line 10). Make sure your trailer is fully loaded when you calculate your weight. Based on the weight of 11,000 lbs. (11,000/4 = 2,750/tire) you stated below, the minimum pressure you should run is 50 psi. I normally recommend 5-10 psi higher than the calculated pressure for some safety. You will want to stay pretty close to this recommendation for ride comfort and to achieve good tire wear. Don’t worry, the tire is engineered for this pressure for the load. The reason the max is 110 psi is the tire is used in some commercial applications that require the additional load carrying capacity.

Please send along any additional questions.

Safe travels.

Al Eagleson ‘ACE’

Segment Manager, Commercial Tires
Off. (289) 499-3240 x202
Cel. (416) 315-9391
Sailun-logo-truck
300-1 Kenview Blvd.,
Brampton, ON, L6T 5E6

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.

[MidwestCamper]

Right, but ambient could be -20 or 90.

Correct and that is irrelevant. Its assumed to be unlikely to be able to drive from one area at -20 to another that is 90 in a single day. At some point some judgment calls would be in order but cold inflation pressure implies tires that are at ambient temperatures.

[MidwestCamper]

Okay, so I have always gone with the crowd on "set them to the maximum cold pressure as listed on the tire" HOWEVER .... I recently put Sailuns on my 337 and, as we have discussed endlessly here, I aired them up to 110 per the tire sidewall but then I decided to send an email to Sailun customer support and check out their response!

Paul, thank you for your inquiry to Sailun Tire and for being a Sailun customer.

In regard to your question about inflation, I have attached the Tire and Rim Association load and inflation table for your size (reference line 10). Make sure your trailer is fully loaded when you calculate your weight. Based on the weight of 11,000 lbs. (11,000/4 = 2,750/tire) you stated below, the minimum pressure you should run is 50 psi. I normally recommend 5-10 psi higher than the calculated pressure for some safety. You will want to stay pretty close to this recommendation for ride comfort and to achieve good tire wear. Don’t worry, the tire is engineered for this pressure for the load. The reason the max is 110 psi is the tire is used in some commercial applications that require the additional load carrying capacity.

Please send along any additional questions.

Safe travels.

Al Eagleson ‘ACE’

Segment Manager, Commercial Tires
Off. (289) 499-3240 x202
Cel. (416) 315-9391
Sailun-logo-truck
300-1 Kenview Blvd.,
Brampton, ON, L6T 5E6

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.

And the truth will set you free! Thank you!