Tire Loading
- Thread starter Titanguy
- Start date
JohnD
Moved on to the next thing...
I was told by not only a service tech at our previous dealership (whom I trusted, but he left the company shortly after he worked with us on a few issues) and the operator of a tire shop that the air in the rear tires should be increased by 10PSI when hauling a heavy load.
What are your thoughts on this?
What are your thoughts on this?
JohnD
Moved on to the next thing...
I know it doesn't increase load capacity . . . I'm guessing maybe a better ride or something?
Our RAM 2500HD has a sticker on the door post that recommends 75 lb rear for heavy loads. I inflated and checked my tire pressures religiously and maintained that cold pressure until I had the truck and rig weighed. We were told at that time to inflate to the cold tire pressure indicated on the sidewall of the tire (80b) in order to achieve the maximum allowed load rating for the tire. The tire was an upgrade from the original tires mounted at the time of manufacture. We now follow the pressures indicated on the sidewall.
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rxbristol
Well-known member
There is an article that covers this exact topic in the latest issue of Trailer Life. It explains the reasoning for the extra 10 psi.
JohnD
Moved on to the next thing...
I just got mine in the mail today . . . I'll check out the article!
Titanguy
Well-known member
Anyone running an ST tire at 75 mph is nuts! The information on sidewall information is good and warrants reading. The information on ST tires dates back to when ST tires were made in the U.S. and is not current.
Here are 4 slides from one of my tire seminars. Believe what you want but ST tires of today are not what they once were.
This is exactly the reason I run 215/75R17.5 H U.S. made tires on my 5th wheel.
Here are 4 slides from one of my tire seminars. Believe what you want but ST tires of today are not what they once were.
This is exactly the reason I run 215/75R17.5 H U.S. made tires on my 5th wheel.
rxbristol
Well-known member
There are many other ST tires of different construction. For example, the Continental HTL2, 215/75R17.5, load range "J", weighs 61 lbs. and rated for 75 mph. Goodyear's G114 come in at 60 lbs.
wdk450
Well-known member
Titanguy:
I saw your oversized tires and wheels special (even put it in the print queue ), and this morning saw a posting on RV nation about getting new tire for their 16K GVW 5th wheel. I repeatedly searched the forum but could not come up with your offer to refer the other guy to. Can you locate it quickly for me to forward?
I saw your oversized tires and wheels special (even put it in the print queue ), and this morning saw a posting on RV nation about getting new tire for their 16K GVW 5th wheel. I repeatedly searched the forum but could not come up with your offer to refer the other guy to. Can you locate it quickly for me to forward?
danemayer
Well-known member
ViAir 450p will handle your tires nicely.
You probably don't need 125 psi in the tires. Check the Goodyear inflation tables for your GVWR less pin weight, plus a margin of 500 lbs.
115 psi might be plenty with your G114s.
But check.
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You probably don't need 125 psi in the tires. Check the Goodyear inflation tables for your GVWR less pin weight, plus a margin of 500 lbs.
115 psi might be plenty with your G114s.
But check.
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Thanks, Dan and Ann,
Good to know about ViAir 450, I'll check it out.
That's a relief that I don't need 125 psi. When I went to goodyear.com/rv, I downloaded an inflation table that doesn't include my tires(LT215/75R17.5H) and says it was last updated in 2005! So I feel a bit directionless. But I'm glad that someone feels that 115 could be sufficient (18K GVWR - 3200 hitch weight + 500 => 14300 / 4 ~ 3600).
I'm new to all this; I appreciate the benefit of your experience.
Good to know about ViAir 450, I'll check it out.
That's a relief that I don't need 125 psi. When I went to goodyear.com/rv, I downloaded an inflation table that doesn't include my tires(LT215/75R17.5H) and says it was last updated in 2005! So I feel a bit directionless. But I'm glad that someone feels that 115 could be sufficient (18K GVWR - 3200 hitch weight + 500 => 14300 / 4 ~ 3600).
I'm new to all this; I appreciate the benefit of your experience.
danemayer
Well-known member
Let me clarify.
18,000 GVWR less 3,200 Pin Weight = 14,800 lbs on 2 axles, or 7,400 lbs on each axle. That's 3,700 lbs on each wheel, if weight is distributed evenly. 500 lbs margin is my opinion of a minimal margin. Add the 500 lbs to each wheel and you'll want a load capacity of 4,200 lbs. Some people might recommend a 20% margin, which would be a load of 4,440.
Here's the table from Goodyear for 215/75R17.5, which is the G114 tire that you have. As you can see, 110 - 115 psi gives you 4,340 - 4,495 lbs of capacity on each tire. That's closer to 20% of margin and is enough margin to deal with uneven weight distribution and inaccurate gauges. Here's a link to the complete Goodyear document.
18,000 GVWR less 3,200 Pin Weight = 14,800 lbs on 2 axles, or 7,400 lbs on each axle. That's 3,700 lbs on each wheel, if weight is distributed evenly. 500 lbs margin is my opinion of a minimal margin. Add the 500 lbs to each wheel and you'll want a load capacity of 4,200 lbs. Some people might recommend a 20% margin, which would be a load of 4,440.
Here's the table from Goodyear for 215/75R17.5, which is the G114 tire that you have. As you can see, 110 - 115 psi gives you 4,340 - 4,495 lbs of capacity on each tire. That's closer to 20% of margin and is enough margin to deal with uneven weight distribution and inaccurate gauges. Here's a link to the complete Goodyear document.
