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Old 07-19-2015, 02:46 PM   #1
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Question Tire Load and inflation Tables Questions

 Here is my Problem. I purchased 6 Samson GL283A 245/70R19.5 steel belted Radial Tires for my Motor home. The front axle is 7000 Lbs and the rear duals is 11000 Lbs total GVWR is 18000 Lbs I weighed My Motor Home axles on a Cat scale. Front 5520 Lbs Rear duals 10420 Lbs GW 1590 Lbs There is no Load Inflation table for this tire. The max PSI is 119 Lbs The Max load is single 4940 at 119 Lbs, Max load Dual at 119 Lbs is 4675 Lbs. The Manufacturer of the Motor Home states on the tire placard 80 Lbs psi on all tires. The tires are really overkill for the weight of the motor home. Without a Load Inflation table I have put 85 Lbs in the fronts and 85 Lbs in the rear. I made a Load inflation table which May not be accurate or valid. Here is what I did.

I divided 119 Lbs in to the max load for the single tire 4940 Lbs =41.51 Lbs per pound of load so if my formula is correct at the motor homes tire placard of 80 lbs X 41.51 = 3320 X 2 = 6641Lbs for the front axle So I went to 85 PSI which gave me 3520 X 2 = 7056 Lbs.

I did the same with the rear Duals at 39.3 Lbs per pound of load 80 lbs x 39.3 = 3144 X 4 = 12576
I went with 85Lbs in the rear duals = 13362Lbs Which is more than enough for the 11000 Lb rear axle.

Here are my concerns. Not enough tire pressure will ruin the tire. These Tire are 16 ply H rated. To much pressure will wear the center of the tire and give a harsh ride and possible handling problems. I contacted Samson Tire headquarters in Akron Ohio They said not to go below 80 PSI. I just want to know that I am safe with the pressures I have choose to use, and won't damage the tires.
Any Help in regards this matter is appreciated.
M H Bell
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Old 07-19-2015, 03:11 PM   #2
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It looks to me that your tires are listed in Michelin's load and inflation tables ?
Load & Inflation Tables | Michelin Truck
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Old 07-19-2015, 03:30 PM   #3
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Camping world has an RV Handbook by Trailer life that has the Tire and Rim Association Ratings for RV Tires. I have referred to mine for my previous 5th wheel and now my MH.

I will attach a pdf of a page in the table that should help.
Attached Files
File Type: pdf table.pdf (679.4 KB, 49 views)
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Old 07-19-2015, 09:27 PM   #4
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The RMA-Rubber Manufacturers Association, of which virtually all major tire manufacturers are members published a Tire Care booklet in pdf form. Chapter 4 pertains to Motorhomes, page 55 states:
"
Inflation pressure recommendations may also be
determined based on the tire manufacturer's
specifications, which define the amount of inflation
pressure necessary to carry a given load. These
inflation pressures may differ from those found on
the vehicle tire placard or certification label.
However, never use inflation pressure lower than
specified by the vehicle tire placard, certification
label or owner’s manual. Nor should inflation
pressure exceed the maximum pressure molded on
the tire sidewall.
Michelin, Goodyear, and most other mfgrs have the same admonition on their websites.
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Old 07-20-2015, 07:22 AM   #5
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Good info Ray but remember once you change to different tire you can't use the placard anymore. My original tires were barely acceptable load wise so I upgraded to a stronger tire.
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