kahoona
North Palm Beach, FL
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I just bought a pair of Sumitomo 719front tires (255/70/22.5 M 16ply rated). I asked what to inflate them too and was told they inflate them to 120psi which is the max on the sidewall. I have always used a load and inflation chart specific to that tire and just figured that I'd find one and determine the proper pressure myself. Not so easy.
In the website of TVC who distributes the brand I could only fond a max pressure and max weight. Not what I need. A series of phone calls and emails yielded a chart but it was made for a different line of tires. More questioning got me the statement that all light truck and RV tires have the same load to psi figures. This could not be true because my old tires (Sumitomo 727's same size) that had different psi figures. I gave up on TVC when they said there was no email or phone number to reach the Sumitomo office or factory and that even they could not contact them.
A number of people used various mathematical formulas and charts to give me everything from 75psi to 135psi. The max is on the sidewall as 120psi but I was told that that does not really apply.
Does anyone have a way to contact Sumitomo? At 120psi it feels like I have wooden wheels but I am not comfortable taking a "best guess" Things sure have changed in customer service these days.
Kahoona
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BB_TX
McKinney, Texas
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Max pressure is always a safe way to go. But I agree, it is not really the best way, especially if your actual weight is well below the max weight rating as the ride will likely be harsh. But if the manufacturer will not provide a chart then an “best guess” is about your only option.
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rk911
DuPage County
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i did a search for 'Sumitomo Tire Inflation Chart' and got several hits.
If you scroll down to the bottom you'll ........er and physical address for the company.
This link includes a tire inflation table. Scroll down a bit to see it.
Hope this helps.
Rich
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kahoona
North Palm Beach, FL
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There you have the problem in a nutshell. That address, phone and email is for the US wholesaler, TVC, and the table is for tires which are Sumitomo are from a from a different line. The folks who answer the phone and email for TVC say that all small truck tires, regardless of line or even brand will have the same inflation for a given load. I can't believe that. they aren't able to give any answer but that one and claim that there is no way for me or even TVC to ask the manufacturer for a chart. Frustrating. I'll run them at max for now but they feel like wooden tires. The Sumitomos that they replaced ran at 110 but they were 727's and have their own table.
Enough ranting. I have found an English language site got the manufacturer in Japan and have sent them a polite request. We will see what happens. They make tennis balls, some DUnlop tires and thousands of other rubber things. They even make some tires in the USA. Amazing.
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rk911
DuPage County
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sorry that was no help for you. i agree that running them at max is your best option.
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stripit
Prescott
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Looks to me you can use the Goodyear tire pressure chart that shows your size tire up to 120 psi, it breaks it down to single or dual. Knowing the weights your coach weighs will allow you to set the correct tire pressues. Tire pressure guide
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BarryG20
Castle Rock, Colorado
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I must be missing something.
Some one posted a load inflation table from Sumitomo tires
The link is talking about their S tires and in the chart below the load inflation table it has the 719's specifically in that chart. Why would you think that the load inflation table does not apply to them?
It also states in the linked "book" as they called it under the section titled
Proper Tire Inflation
"Consult the air pressure guidelines in this book, or refer to the tire sidewall or pressure charts from the Tire and Rim Association. When
speeds are constantly above 70 m.p.h., it is recommended to use maximum air pressure for good wear and
performance."
Again perhaps I am missing something and very well may be, but it looks clear to me
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CapriRacer
Somewhere in the US
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And allow me to confirm that the load vs inflation pressure thing is regardless of who manufactures the tire. It's a Tire Standardiztion Organiztion thing. In the US, that's The Tire and Rim Association.
You claim your previous tires had different values, and that could be because you had different Load Ranges.
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kahoona
North Palm Beach, FL
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BarryG20 wrote:I must be missing something.
Some one posted a load inflation table from Sumitomo tires
The link is talking about their S tires and in the chart below the load inflation table it has the 719's specifically in that chart. Why would you think that the load inflation table does not apply to them?
It also states in the linked "book" as they called it under the section titled
Proper Tire Inflation
"Consult the air pressure guidelines in this book, or refer to the tire sidewall or pressure charts from the Tire and Rim Association. When
speeds are constantly above 70 m.p.h., it is recommended to use maximum air pressure for good wear and
performance."
Again perhaps I am missing something and very well may be, but it looks clear to me
No, I think it is me that is missing something. I did not understand what that bottom chart was for. Looking closer it does have my size then across the top it does have 719. where the columns for those meet it says H. My load range id H. Just to confirm are you saying that it is saying that the above table does apply to my tires and that the section at the top about 788's and 948's is just a blurb about those tires. If so thank you for explaining that. I am grateful to you for letting me know and apologize for any confusion I have created. I am getting too old for this complicated stuff!
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CA Traveler
The Western States
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The inflation tables are designed (hopefully) to provide the optimal conditions for a given weight. More pressure up to the max can cause more tire rounding and less traction and center wear for example. Inflation for all tires on a axle is the same and based on the heavest side.
Tires aren't always what they should be and I remain negative on Michelin and Goodyear due to my experience with cracking and other issues.
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