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Old 06-18-2016, 08:31 AM   #1
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What pressure

I just had 6 new tires installed. They are 120 PSI max. I had MH weighted They only did steer axle (6600 lb) and drive axle (12540 lb) Total weight 19140 lbs. This was weighted with full tanks and full of gas. MH fully loaded for road. Tire place told me not to go under 105 PSI. Also 16 ply tires. What pressure should I use. I have 110 in them now.
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Old 06-18-2016, 08:37 AM   #2
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need more info.
What brand and model of tire?

You will also need to add a margin because you can't assume the left & right side of each axle has the same weight.

"Usually" the duals have slightly less air pressure because they "usually" have less weight per tire. But you need to go by the tire chart from the mfg.

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Old 06-18-2016, 08:40 AM   #3
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Quote:
Originally Posted by Texbeachbum View Post
I just had 6 new tires installed. They are 120 PSI max. I had MH weighted They only did steer axle (6600 lb) and drive axle (12540 lb) Total weight 19140 lbs. This was weighted with full tanks and full of gas. MH fully loaded for road. Tire place told me not to go under 105 PSI. Also 16 ply tires. What pressure should I use. I have 110 in them now.

Can't answer without a tire size. The 16 ply is relatively meaningless. Is it simply derived from load range. These commercial all steel tires physically have one sidewall ply and 4-5 tread plies.
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Old 06-18-2016, 08:47 AM   #4
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Sorry coffee hasn't clicked in yet. Samson Advance Radial Truck GL283A 245/70R-19.5

Was weighed at a CAT scale
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Old 06-18-2016, 08:51 AM   #5
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Quote:
Originally Posted by Texbeachbum View Post
I just had 6 new tires installed. They are 120 PSI max. I had MH weighted They only did steer axle (6600 lb) and drive axle (12540 lb) Total weight 19140 lbs. This was weighted with full tanks and full of gas. MH fully loaded for road. Tire place told me not to go under 105 PSI. Also 16 ply tires. What pressure should I use. I have 110 in them now.
What brand tires do you have? Most have Michelin RV Tires | A Better Way Forward or Goodyear RV Tires – Performance, Durability and Comfort

What size tires to you have? You mentioned you have 16 ply tires which is Load Range H.

Once you know these, go to the tire inflation table for the manufacturer. It is best to get 4 (or 6 if you have a tag axle) corner weights because you can not assume the load is evenly distributed across the given axle.

For Michelin, here is the Michelin RV Tires | View Michelin RV Tires load and inflation tables for motorhomes and recreational vehicles. | Michelin RV Tires. For Goodyear, go http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf.

The following paragraphs are taken from an article in FMCA Diesel RV Club Newsletter authored by Dick Lorntson: (Full article is in the attachment)

"All tires on the same axle must carry the same air pressure but the front or rear axles may carry different air pressures based on the recorded weights. For instance, both front tires must be the same and all four rear tires must be at the same pressure. Tag axle tires should also carry the same pressure.

I will give a good example of why knowing your 4-corner weights are so important. Using my own 40-foot Damon on a Freightliner chassis, I know that the weights are as follows:

Left front 5,250 lbs Right front 5,600 lbs
Left rear 9,200 lbs Right rear 10,150 lbs"

Truth be known, I can not tell you how much air to put in your tires because there are too many unknowns at this point.
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File Type: pdf Pages from DRVC_Travelore_160634.pdf (556.6 KB, 15 views)
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Old 06-18-2016, 08:52 AM   #6
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Go to the Samson website and look up your tire size and weight. They will have a pressure chart.
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Old 06-18-2016, 09:06 AM   #7
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Quote:
Originally Posted by Texbeachbum View Post
Sorry coffee hasn't clicked in yet. Samson Advance Radial Truck GL283A 245/70R-19.5

Was weighed at a CAT scale

You would need to check a Samson pressure chart to be sure, but interpolating from a Michelin chart, you can support you weight with a comfortable safely margin at 90 psi all around.
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Old 06-18-2016, 09:31 AM   #8
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Our coach has a tag on the wall to the left of the drivers seat that has the manufacturer's recommendations for inflation. You likely also have a tag like this. You can use those figures until you get all the weights for the corners and then use the tire makers recommendations from their web site.
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Old 06-18-2016, 09:43 AM   #9
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Agree with B Bob. Manufacture recommendations consider coach balance and tire spec. Just using tire recommendation on my coach were very different. See attached.

Notice the difference between drive axle and tag, with same tire size.
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Old 06-18-2016, 10:22 AM   #10
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Our coach has a tag on the wall to the left of the drivers seat that has the manufacturer's recommendations for inflation. You likely also have a tag like this. You can use those figures until you get all the weights for the corners and then use the tire makers recommendations from their web site.
That plate says 75 PSI
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Old 06-18-2016, 10:25 AM   #11
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What pressure

I've been sort of keeping an eye on these Samson tires. Price is very attractive and users seem quite satisfied. But for some reason they haven't (can't?, won't?) produced an inflation chart. From what I've seen their warranty excludes failure due to improper inflation, yet there is no published information as to what is proper inflation. Sketchy, at best.
My question is: Separate and apart from warranty issues, could you take or create a composite number from the charts of other established tire makers. Same size, load range, etc. Michelin, GY, Toyo, Firestone, Hankook, etc., etc. I don't imagine the numbers could be that different for tires of the same spec.
Thoughts?


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Old 06-18-2016, 10:45 AM   #12
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If that placard from the coach builder says 75, you can use it assuming it is for the same tire size, which is also shown on the placard. However, it doesn't hurt to go a bit higher to be sure.
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Old 06-18-2016, 11:30 AM   #13
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Quote:
Originally Posted by Texbeachbum View Post
That plate says 75 PSI

Looks like75 psi is just enough to carry your current weight. I would add a little margin.
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Old 06-18-2016, 11:35 AM   #14
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Quote:
Originally Posted by JFXG View Post
I've been sort of keeping an eye on these Samson tires. Price is very attractive and users seem quite satisfied. But for some reason they haven't (can't?, won't?) produced an inflation chart. From what I've seen their warranty excludes failure due to improper inflation, yet there is no published information as to what is proper inflation. Sketchy, at best.
My question is: Separate and apart from warranty issues, could you take or create a composite number from the charts of other established tire makers. Same size, load range, etc. Michelin, GY, Toyo, Firestone, Hankook, etc., etc. I don't imagine the numbers could be that different for tires of the same spec.
Thoughts?


John & Diane, fulltiming since '12 02 DS, FL, Cat, '04 Element NHSO RVM103
As long as you care comparing the same size tire with the same load range, the load carried at max tire pressure is the same. I am in a similar position with Sailun S-665 drive tires. The load at max tire pressure listed in their commercial tire catalog is the same as Toyo. Toyo does have a tire inflation chart.
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