What tire pressure to run for 110 PSI Cold Max

ddj

Member
I have 235/85r16 tires and it shows 110pounds max pressure cold on the sidewall. I checked the tires and all four had 80 pounds,is this the right tire pressure? I'm sure it tells in the manual but I can't find it right now.By the way the tires are on a 37ft Grand Canyon 5th wheel.
 

trdeal

Past North Carolina Chapter Leader
I asked my dealer this question. The service guy said to run whatever is on the sidewall. We have a 2005 Mt. Rushmore. My sidewalls call for 110lbs. This is what we run in them. We have made several trips to the beach and have not had a problem.
 
K

Ken Washington

Guest
DDJ,
I also have the same unit you have and I run 95 lbs. I think that 110 is too high because you are not putting the max load on them. This has been a big issue on this fourm and everyone has a different view on what's right. Just do a search and you will see.
Ken
 

jpmorgan37

Well-known member
I run 110 pounds cold. The tire manufacturers recommend 110 pounds cold. Tire engineers recommend 110 pounds cold. The experts who do tire testing and evaluation recommend 110 pounds cold. At our seminar at the last Heartland rally, not only was it recommended to run at the stated sidewall pressure, but to spend some money and get an accurate tire guage so that you are sure of the exact pressure.
 

ct0218

Well-known member
I agree with John, and I do the same. My Mt Rushmore weighs in right at max GVWR. Also, see Jeff's post in this section dated 11-11-04, Load and Inflation Pressures. Reducing pressure reduces your capacity. You really need to weigh your rig, loaded normally, to know for sure. Over inflating , as long as it is at or below sidewall rating, is better than underflating. Underinflation increases the heat generated when rolling and adversely affects the tire life.
 

BigBlue

BigBlue
RV Today did a segment on tire pressures when they covered weighing your rig. They referred to the tire manufacturers load rating guide which describes the pressure to run for the weight you carry. You need to get your trailer weighed and adjust the tire pressure accordingly.
 

jpmorgan37

Well-known member
While I agree whole heartedly with Clark and Jim about getting the trailer weighed so that you know what weight is on each tire, there is one other factor that is frequently overlooked on tires and that is the stress that is put on them in side to side movement which we get when backing into a site. Load ratings are determined by the vertical load placed on the tire. The horizontal load from turning can be, and often is, significantly higher and can damage or weaken the sidewall strength. With the air pressure set at the tire manufacturers recommended pressure, this reduces the chance of damage to the tire sidewalls from this stress factor.

ddj, when my Grand Canyon came from the factory, it had 75 psi + or - a couple in each tire. Before I left the dealer, they had aired them to 110 psi. I, so far, haven't had a problem with my tires and I'm somewhere around 10,000 miles and they are the original Trail America, made in China tires. Today, my trailer gross weight is slightly over 16000 pounds and is as balanced as I can get it. My pin weight is about 3200 pounds. I hope this helps.

John
 
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ct0218

Well-known member
John is correct about the pressure on the sidewalls in a turn. Better to lose a little rubber scrubbing on pavement than to have the sidewall distorted from a tight turn at low pressure, that has to affect the belts, etc. Watch the distortion of the tires in a tight turn. I see cars and trailers regularly that have tires bulging out because of low pressure, and I'll bet that a large percentage of tire problems are caused by low pressure. The tires on my Mt. Rushmore were inflated to 80 PSI when it was delivered to the dealer. I, too, inflated them to 110 before I headed home.
 
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