At what psi can I travel 65-75mph?

Industry standards dictate that tires with the ST designation are speed
rated at 65 MPH (104 km/h) under normal inflation and load conditions.

What are the industry standards and who decides what they are or should be… it is my guess between TIA and the RMA both trade organizations representing tire mfg. trough Gov. lobbying efforts…

But don’t kid yourself though their concern is to protect the tire industry not your safety… safety is the leverage word used for arm twisting policy making… their primary job is to protect the industries through lobbied regulation that shields them and shifts their burdens from their hands, often using the NHTSA for their platform…


“TIA's TirePAC was created shortly after the tire recalls of 2000 to assist those in Congress who assist the tire industry. TirePAC helps to ensure the election and re-election of officials who are friendly to the tire industry, as well as establish and maintain solid relationships with elected officials who support the interests of the tire industry. TirePAC allows each member of TIA to be heard more effectively on Capitol Hill.”

“The Rubber Manufacturers Association (RMA) is the national trade association for tire manufacturers that make tires in the U.S.
Technical and Standards formulates tire industry positions on domestic and international standards, coordinates industry positions relative to governmental rulemakings and specifications, and develops, publishes and disseminates tire safety, care, and service information.
Through the Tire Engineering Policy Comittee; RMA: Develops and recommends policy positions on engineering matters Implements engineering matters Reviews and approves industry response to rulemaking dockets Through the Tire Publications and Information Committee; RMA: Develops and drafts publications concerning tire safety, service, maintenance and care for all types of tires. Responds to inquiries, and establishes industry positions on procedures for proper tire service. “


Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

I would take this to mean that the cold PSI is obtained from the inflation/load chart for the tire and using that pressure plus 10 PSI would prevent tire overheating to more than it would under normal load and pressure…


Do not exceed the maximum pressure for the wheel.


The wheel is the tire and rim combination, the maximum pressure for the wheel would be the lower of the PSI rating of the tire or the rim… the lower, normally being the tire for OE (by law)..., meaning the added 10 PSI must still be at or below the Max sidewall PSI, or the speed is still restricted to 65 MPH…

The why it written might be confusing but IMHO airing the tire to 10+ the maximum PSI is a sure way to cause your tire failures…

GOOD LUCK WITH THAT…

OH YA GOOD GOING GOOD YEAR… ANOTHER NON ANSWER FROM YOU CS DEPT…

Simple. Follow manufacturers specs. Need more speed, buy a tire with the right specs. Otherwise sit back and enjoy the scenery.
I thought RV'ing was suppose to be relaxing. Doing 75 does not fit in that category to me so why leave home.....:h

I read the email to mean that you could go up 10psi for rated load (even max) as long as you don't exceed the pressure for the wheel. At least it is ambiguous on that point, but I agree not going past max psi. This is why I like to see printed, published documentation.

Everyone seems to be caught up in the revelation that adding 10psi lets them travel at up to 75mph.

What was not stated is that max sidewall pressure is just that MAX PSI!!!! You guys are assuming that you can exceed the max sidewall PSI. They never said that. What was said is that if your psi for your load has you at a lower than max psi value, then you can add up to 10psi for travel between 66-75mph. The problem here is that most RV's are already placarded with a pressure that IS the max sidewall pressure.

Now if you really need to go faster, then go out and buy a tire that has more capacity and a higher sidewall max psi.

I'll be waving to you from the right lane running at 62-65.

Keith

Francesca Knowles wrote:
^..^.^.^.^.^.^.^.^.^.^.^.^


See what I mean, John? ;)

So you deem it case closed, so there can be no further discussion? Typical. BTW I have a vested interest in getting to the bottom of this, though my ST tires rarely see over 50mph.

^..^.^.^.^.^.^.^.^.^.^.^.^


See what I mean, John? ;)

full_mosey wrote:

Francesca Knowles wrote:


I'd much appreciate a copy of the original E-mail you received from Goodyear.


Francesca

Hi Francesca;

I posted the body of Goodyear's reply by copy and paste. I did blank out my name and email addy. I can edit the post to show where I blanked out my personal info.

I don't see anything remarkable about their reply except to authenticate the link from Tire Rack.

HTH;
John

Francesca wants it because she has an agenda also, Just saying.

So, I find that reply from GY interesting. CS reps are saying you are allowed to do this, but the info has been scrubbed from their website. It used to be in the load inflation tables and the product briefs. Now it is nowhere to be found on Maxxis or GY sites.

Still seems very conflicting. The 65mph speed limit is published in every document on ST tires out there. Sometimes it is even molded right into the tire, yet an email states the the limit is really 75mph. This would also mean airing the tire 10psi higher than what is molded into the sidewall in some cases. Seems fishy to me.

Because most everyone wants to go the speed limit, they are willing to use the spec that is most convenient. Hell that is what I do :)

Francesca Knowles wrote:


I'd much appreciate a copy of the original E-mail you received from Goodyear.


Francesca

Hi Francesca;

I posted the body of Goodyear's reply by copy and paste. I did blank out my name and email addy. I can edit the post to show where I blanked out my personal info.

I don't see anything remarkable about their reply except to authenticate the link from Tire Rack.

HTH;
John

Hi jadatis;

jadatis wrote:
Once read for ST tires that for higher speed a percentage higher pressure then acording to the lists, and for better handling quality , also a percentage highening up.
If then the new pressure came above maxloadpressure, pressure needed for the maximum load , so reference-pressure, it may not be more then 10 psi.
So my calculation of 44psi + 10% =48,5 psi already has that percentage , wich I mean to remember 2 x 5% , higher then acording to the list,in this case my extra save list, and so stays under the 50+10 psi , and is allowed.
You are also allowed to drive with 60 psi , thoug it would not be good for grip and keeping the screws in the wood of the TT.

You can even stay at normal rubber valves, wich are allowed a cold pressure of 65 to 70 psi ( depending on the brand) with 26 psi extra for higher temperature in the tire, to the mildest american standard.
This 26 psi makes it possible to fill at 65dgr F a pressure of 70 psi and if the inside tire temperature gets boiling point of water ( 100dgr C/200dgrF?) , wich it can incidentialy get by the heat of the brakes, transported trough the rims, the pressure stays below that 96 psi.
High pressure snap in valves wich are alowed for 90 psi maximum cold pressure , or metal valves for over 150 psi.

Yes, I understand, and thank you again for those calculations.

Are your formulas are based on industry standards in Holland? I say that not to challenge, but only to say I must interpret the standard sent to me by Goodyear. As a member of the Tire and Rim Association, Inc., Goodyear is compelled to adhere to those standards in order to use the ST designation.

I base my calcs, the 60psi, on the phrase 'rated maximum load'. If Goodyear had said 'rated minimum load' per the tables, then your calcs would be within the Goodyear PBS #2011-13 which is meant to advise Goodyear dealers.

The issue is not clear yet.

HTH;
John

full_mosey wrote:
We have our reply from Goodyear

From: goodyear_cr@goodyear.com on 07/25/2013 01:13 PM

Sent by: Goodyear Tire & Rubber Company Consumer Relations 728 1144 East
Market Street Akron, OH 44316 Voice #: 800.321.2136 Fax #:
330.796.6829

Mr. ,

The max load is 1,360lbs at max 50psi.

Industry standards dictate that tires with the ST designation are speed
rated at 65 MPH (104 km/h) under normal inflation and load conditions.
• Based on these industry standards, if tires with the ST designation are
used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is
necessary to increase the cold inflation pressure by 10 psi (69 kPa) above
the recommended pressure for the rated maximum load.

Do not exceed the maximum pressure for the wheel.

Jennifer - Consumer Relations



From: on 07/24/2013 01:11 PM AST




From:


To: goodyear_cr@goodyear.com
cc:
Subject: Contact Us request from www.goodyear.com



A Goodyear website user has submitted a request through the corporate
contact form. Please address the concern accordingly.

Name:
Email:
Phone:
Address:


, 0
Message:
Looking for ST trailer tires. What is the status of your Document PSB
#2011-13 with Subject: Tires for Trailer Use Only: General Information ?
What is the max load and psi of your Marathon 175/80/R13 between 66 and
75mph?

If you are not the correct recipient, please notify the Goodyear Global Web
Operations team of the email error and we will update our website contact
list.

This is the same as the contents of Goodyear's PSB #2011-13 which we have discussed beforehand. I believe we can say the PSB is in effect.

... at speeds between 66 and 75 mph:

Tire: Add 10 to 50psi means inflate to 60psi.

Wheel: Dexstar 17-229 is rated 1660lbs 65psi.

HTH;
John

You're my hero, John! Straight from the horse's mouth, no nonsense.

I'd much appreciate a copy of the original E-mail you received from Goodyear. I'd like to make a PDF of it since I fully expect a mere "quotation" of your post to be discredited by by those whose agenda it doesn't serve.

One picture is worth a thousand words, no matter how loud...right?

I'll P.M. my E-mail address to you and hope to receive a forwarded copy.

Thanks again!

Francesca