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Old 10-24-2021, 11:17 AM   #1
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Tire pressure help, sorry to ask again

Had a front tire blow out and I have to say I am overly sensitive now and our first trip since the blowout is coming up in a week. We full time so when we weigh we are fully loaded with fuel, water, etc.

I put two new Toyo 144's on the front and would really appreciate any thoughts from those that follow the charts. I know some of you have your own reasons for what you do but I want to know if I am following the chart correctly on this post.

Toyo M 144 tires, 315/80R 22.5
Toyo specs from the sidewall is
MAX load single 9370 lbs at 130 PSI Cold

Weight from the CAT scale (I know it would be best to weigh each tire individually and plan to do so as soon as possible)
Total front weight of 8127 pounds

Attached is the only load chart I could find but it has 3 different sections for my tires. Only the forth one has a notation by it and that is to compare it to a different size Michelin. Any thoughts on how to read this and get the right answer. In the old days I would make a phone call but nowadays, I don't think I would get someone who could really answer it.

Sorry for the pics, tried to copy and paste just the info regarding my tires. The PSI chart would go over the tire size chart
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Old 10-24-2021, 11:28 AM   #2
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Something seems off here. A 45 diesel pusher motorhome and your front end only weighs 8127 lbs?
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Old 10-24-2021, 11:43 AM   #3
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With 315/ 80's, you must be talking per side?
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Old 10-24-2021, 12:53 PM   #4
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Quote:
Originally Posted by 757driver View Post
Something seems off here. A 45 diesel pusher motorhome and your front end only weighs 8127 lbs?


Agreed, something seems off. Do you actually still have the allegro bus? Pls reverify your weights?
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Old 10-24-2021, 01:03 PM   #5
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On my 36' my front axle is about 8300. I with the others, somthing is wrong. Until I figured it out. I error on the high side. Use the 130 psi.
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Old 10-24-2021, 01:24 PM   #6
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Your appropriate weight number for your coach is apparently 8100 pounds per side. A front axle on a coach your size should be in the 15K - 17K range. On the chart you show, you should be running 120psi.

With that said, I know you're sensitive to blowouts, but see how the coach rides. Play with the numbers a little and see if 115 psi works. A few ways to check. If a coach tire is running underinflated, you can actually smell it. The smell of rubber. I'm sure you had that smell when the tire blew. Look to see if its squatty, more so than the rears. Lastly, watch it for wear, if the outer edges start to wear more, the pressure is too low.

Regarding the above....I'm not talking about running the tires underinflated, but getting them just right for your coach. Overinflated tires make for a miserable ride and beat the coach to death. On mine, I've played with the adjustments to where just a few pounds make a difference. I started mine at 115 psi and adjusted them to 112 psi for best ride and wear.
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Old 10-24-2021, 01:44 PM   #7
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Hey Don ---not sure about that. On the chart he shows (which I found online also) the SECOND group of numbers for 315 80R22.5 tires shows a max sidewall pressure of 130 and max load of 7390 (for duals) .... which sounds like his his actual tires?? (Boy .... Toyo could definitely be clearer on these charts!). IF that is the case, then for singles, single sided load of 8127, that looks more like 110 psi (again, this is for the second section for 315/80R22.5 tires).

Or am I off in my interpretations of this??
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Old 10-24-2021, 01:51 PM   #8
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The 4 asterisks denote information applicable to the M320Z, which you are not running. That leaves the other 2, 315/80R 22.5 tables. Both indicate Load Range L. I’d go with the lowest common denominator, which are the recommended pressures on the top line.

Since you have indicated that the weight is based on total axle weight, rather than axle end weights, you need to account for side to side variations in weight. Obviously, you’ve divided the total front axle weight by 2 to come up with 8127lbs. There could be a difference of several hundred pounds or more from side to side. At the very least, you need to round up your figure to 8270lbs, which shows 120psi as the minimum pressure to support the load.

Depending on any imbalance in weight, you may opt to inflate to 125psi, which would support 8810lbs. Tireman9 frequently advises to add 10% to the recommended minimum chart pressures. That would put cold pressure above the stated maximum of 130psi, which is a practice generally frowned upon.

Have you asked a manager at the tire shop that installed the new tires for an explanation of why the chart shows different load ratings and pressure recommendations for the same size tires with the same load range rating?

Theoretically, most, if not all, LRL tires would have the same load ratings and pressure recommendations. As an example, the Michelin X-Line Energy Z Coach tires, in a 315/80R 22.5 have a load rating of 8270lbs at 120psi.
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Old 10-24-2021, 02:30 PM   #9
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Quote:
Originally Posted by 757driver View Post
Something seems off here. A 45 diesel pusher motorhome and your front end only weighs 8127 lbs?
I have a 40 weighs in at 9820
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Old 10-24-2021, 02:32 PM   #10
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To be totally safe forget load/inflation charts, what does the Federal Tire Placard in your MH state? Inflate to those pressures unless you have overloaded your MH.


Load/inflation charts show the minimum pressure to support the load, which means the tire is operating at 100% capacity.
Tireman9 says when using load/inflation charts to add 10%-15% to that listed pressure, not to exceed sidewall maximum. If you don't have 4-corner weights figure each corner weighs 60% of axle weight to be safe.
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Old 10-24-2021, 04:05 PM   #11
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Quote:
Originally Posted by MN_Traveler View Post
Hey Don ---not sure about that. On the chart he shows (which I found online also) the SECOND group of numbers for 315 80R22.5 tires shows a max sidewall pressure of 130 and max load of 7390 (for duals) .... which sounds like his his actual tires?? (Boy .... Toyo could definitely be clearer on these charts!). IF that is the case, then for singles, single sided load of 8127, that looks more like 110 psi (again, this is for the second section for 315/80R22.5 tires).

Or am I off in my interpretations of this??
I couldn't open up that entire chart, it opened in two pages, I may have misaligned them, but 130psi sounds high.
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Old 10-24-2021, 04:34 PM   #12
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Quote:
Originally Posted by Dutch Star Don View Post
I couldn't open up that entire chart, it opened in two pages, I may have misaligned them, but 130psi sounds high.


I was saying that on that line, the max sidewall pressure is listed as 130 ... which would put his tires at 110
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Old 10-24-2021, 06:33 PM   #13
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I'm sorry all, I come for help and then provide the wrong info. The 8127 is the total divided in half so the total from the CAT scale is 16,254 pounds.

I will have to take a look at the placard on the coach and see how that compares to the guide from Toyo.
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Old 10-25-2021, 06:16 AM   #14
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Quote:
Originally Posted by brandss View Post
Had a front tire blow out and I have to say I am overly sensitive now and our first trip since the blowout is coming up in a week. We full time so when we weigh we are fully loaded with fuel, water, etc.

I put two new Toyo 144's on the front and would really appreciate any thoughts from those that follow the charts. I know some of you have your own reasons for what you do but I want to know if I am following the chart correctly on this post.

Toyo M 144 tires, 315/80R 22.5
Toyo specs from the sidewall is
MAX load single 9370 lbs at 130 PSI Cold

Weight from the CAT scale (I know it would be best to weigh each tire individually and plan to do so as soon as possible)
Total front weight of 8127 pounds

Attached is the only load chart I could find but it has 3 different sections for my tires. Only the forth one has a notation by it and that is to compare it to a different size Michelin. Any thoughts on how to read this and get the right answer. In the old days I would make a phone call but nowadays, I don't think I would get someone who could really answer it.

Sorry for the pics, tried to copy and paste just the info regarding my tires. The PSI chart would go over the tire size chart
You have to look back( 8127lbs+10% )/2 in that list is 8940/2= 4470lbs. But it ends at 80psi.
Checked the list to made with the European formula for all kind of tires, so a good list

Then second , these tires max speed is mostly 75mph or 81mph, wich allows more deflection.
What is your used max speed, and what pressure did you use in front.

So I filled it in my made motorhome-calculator.
But my lunch-brake is over, so to be continued.
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