Need tire inflation by weight for Sunitomo 719 tire

[kahoona]

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.

[4x4van]

As has been said, Load tables for tires are standardized and should be consistent across all brands, assuming the same size/load range. In the absence of having those tables and your actual axle weights (4-corner weights are best), you can use the Federal Tire Info label on your RV (on or near the drivers side door/position) that actually lists your max GAWRs and the pressure needed for those weights using stock size tires.

I can pretty much guarantee that the tire sidewall max is too high for your application, and should not be used. The dealer who sold you the tires should have checked that Federal Tire Info label, NOT simply gone with the max pressure listed on the tire. That's not only lazy, but could even be dangerous.

[CapriRacer]

And just to be clear:

The tables are MINIMUMS, not recommendations.

Plus, inflation pressure doesn't have as much effect on wear as alignment or even position on the vehicle. In passenger cars, the steer tires wear in the shoulders and the drive tires wear in the center, at about the same rate.

That means that in passenger cars, tires on a RWD wear differently, but at the same rate, so tire rotation gets more miles out of a set.

In FWD, the steer tires and the drive tires are the same, so generally the wear is even, but more rapid than the rears. Tire rotation is so the tires wear out at the same time.

I suspect the same is true of trucks and buses, although you don't find many FWD trucks or buses.

[kahoona]

CA Traveler wrote:
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.

Having apologized for not figuring out the information offered on the website I was going to shut up but you made three good points which I agree with. . As you mentioned too many psi for the load does make the tire wear in the center and also reduces traction. That is why I always (as you also suggested) find and use the manufacturers load and inflation for that tire.
I also share your mistrust of Michelin and Goodyear. I had a set of Michelin RV tires begin to crack in the sidewalls as they hit five years and had to replace them. I also had a set of Goodyear RV tires that began blowing out at around five years. I an anal about tire pressure and I also check temps with an IF thermometer at every stop. Thus the Sumitomo's.
Thanks all for the help.

[BarryG20]

Well I may be reading to much into it but yes I think the table applies to your tires. Why would they provide a load inflation table and have a specific set of tires listed and the load inflation table not be for them. It appears on the second chart that all the tires in that chart are for their "S" series of tires(I have no idea if Sumitomo has other lines of tires that are not part of their "S" series)

Many of the load inflation tables I have seen encompass multiple tires. I have seen them broken out by specific type tires, or under specific categories ie rv tires, or truck and bus tires before or just by size for their entire line. The Tire and Rim Association I think and I may be wrong has set standards that size and load rating and psi requirements for that are standard across all tires regardless of brand. Load range A, B, C, D, E, F, G, H in a specific size should have the same load inflation pressures. I mean what good would the rating be if a load range E tire didn't mean the same thing across different tires in the same load range and in the same size. Are there exceptions probably there seems to be in everything else but they certainly aren't going to be way different.

Remember the tables are a starting point. I would not go under the recommended inflation for a given weight but you can certainly go higher as you may find handling, wear and or performance is better on a specific vehicle at a higher pressure than stated due to specific characteristics of that vehicle. A perfect example would be the highly likely situation where an rv is not really properly balanced from one side to the other. Yes you get an axle weigh of say 7000lbs so you divide by two to get 3500lbs a tire. That works as long as the axle weight is evenly split between the two tires but it is not that uncommon for an rv to have one side heavier than the other. In which case it could be enough to increase the inflation pressure on both tires to cover the lopsided weight.

Sorry, getting longwinded bottom line is I would have no issue whatsoever in using that load inflation table for your tires based on what I read in that link.

[CA_Traveler]

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.

[kahoona]

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!

[CapriRacer]

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.

[BarryG20]

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

[stripit]

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

[rk911]

sorry that was no help for you. i agree that running them at max is your best option.

[kahoona]

rk911 wrote:
i did a search for 'Sumitomo Tire Inflation Chart' and got several hits.

If you scroll down to the bottom you'll find a phone number and physical address for the company.

This link includes a tire inflation table. Scroll down a bit to see it.

Hope this helps.

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.

[rk911]

i did a search for 'Sumitomo Tire Inflation Chart' and got several hits.

If you scroll down to the bottom you'll find a phone number and physical address for the company.

This link includes a tire inflation table. Scroll down a bit to see it.

Hope this helps.

[BB_TX]

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.