Correct Tire Pressure

[OldCoot]

Originally Posted by ProjectPro

FR put 205 75 D14 LR C (50 PSI max) on my 2012 VFK27. I'm replacing them with Goodyear / UHaul HMG 2020 LR D (65 PSI max). I tow at about 60 MPH on the Interstate because the trailer seems happy at that speed. I'll weigh the trailer this Friday, but I think it will weigh in at about 6700 pounds. Do I need to make a trade-off between maximizing tire life (65 PSI) and reducing trailer bounce (55 or 60 PSI)?

IMO, I don't think you can tell any difference between 65# and 55# as to the bounce.

[jadatis]

Originally Posted by Tireman9

Maybe you need to talk directly with Goodyear customer service and not to depend on Tire Rack. They are not saying an increase in inflation is acceptable for any ST tire.
Goodyear Customer service is very clear. You should not exceed the inflation associated with the tire max load, i.e. the inflation molded on the tire.
.

Did contact goodyear as answer to a former question about the difference between dual and single load , so they probably began to think I am becomming a nusance. Jennifer Chapman adviced me to buy a yearbook of TRA or ETRTO.

But searching for it again I came to this topic of augustus on another forum where Jared J asked about ST tires and Jenifer gave him the answer I need.
Trailer tire max speed. - Fiberglass RV
This shows that goodyear also allows that 10 psi above referencepressure for ST tires. Yust the same as tire-rack wrote.

So its alowed for ST too to use for instance 90 psi in a 80 psi given cold pressure on sidewall.

so now this is aknowledged by a Trusted party for tireman 9, we can go on with my advice of using it for giving the tire the lesser deflection a LT tire would have.

Only risk could be for the valves, but mostly they are metal valves I think that can stand a cold pressure of over 145psi .
Also the rimm maximum presssure can be an obstacle still, I asume that given maximum is also cold pressure and a pressure rising by temperature rising in the tire is included, yust as it is for valves and tires.

[Tireman9]

OK this topic of speed on ST tires just will not stop.
I believe there is a serious problem with going outside the normal application. There is also a problem when using TRA or ETRTO or JATMA published books and saying that what is published must apply to all tires.
This is simply not true.
It may be better to think of the published books more as GUIDES than standards. It is easy to find numerous tires with load & inflation numbers provided by the manufacturer of the tire to be different than the numbers in the books. Does this mean you can apply the load published by Michelin for a MAXXIS tire? I think Maxxis might object.

There are also some implied assumptions that tire engineers will follow but are not clearly spelled out in the published books. Sometimes we even see employees of a tire company, who do not have years of experience and responsibility as tire design engineers, providing inconsistent answers.
The speed limit on ST tires is such an example.

We see that in some cases the "Industry standards say +10psi allow speed to 75mph and an additional -10% load allow speeds to 85mph but we also have verbal and written statements saying not to exceed 75mph. We may see a statement that suggests it is acceptable to exceed the inflation molded on the tire sidewall that is associated with the max load for that tire. I have personally been told by the representative, that they have discussed this internally and the policy is that the inflation associated with the max load is NOT to be exceeded.
But since so far I have not received a reply in writing I cannot provide "proof" of that statement.

As a result I have asked the rep from Goodyear for a meeting in Akron, so we can get clarification once and for all. If they are willing to meet I will report back what I learn.

[5verdriver]

Here's a novel idea ....keep it at 60-65mph and keep your pressures at sidewall numbers and all is well. Who needs to tow a TT/5er at 80-85mph?

[another_newfie]

Nevermind that, who needs to 'drive' at that speed, let alone tow. That sort of speed belongs on a track.

[kerrlakelover]

Thanks for chasing this for us Tireman!

[schrederman]

Yep, I'm pretty much a 65 MPH guy with max sidewall pressure guy. I have always run my vehicles at max sidewall pressure, too, even when not towing.

[jadatis]

What I am not trying to say , is that you should drive faster then 65m/h.
In Holland the maximum speed for trucks is 80km/50m/h, also did go for cars up to 3500kg/7700lbs with a trailer behind it.
Lately for the last it is highened up to 90km/56m/h so still under 65m.h
In Germany for trailers you have to have a sticker with some demands to the trailer to drive 100km/62m/h and even in france it is allowed.

The only thing is what I tried to make clear , is that it is allowed to use a pressure of 10 psi higher then that pressure written on sidewall or belonging to the load-letter ( E-load fi with 80 psi).

Though the tire-makers dont support extra maximum load for that, the tires would last longer then when 80 psi used, asuming the used loads on trailer-tires always come close to the maximum load.

Then everybody happy , also the tire-maker, because he allows 90psi