Quote:
Originally Posted by CapriRacer
I hope you are aware that medium radial truck tires are inflated to over 100 psi
|
I know the 400psi number was referring to truck tires. I also posted a source suggesting 200psi minimum burst pressure for passenger car tires. Either way about 4 times the listed maximum. And I understand that running conditions can increase pressure, so you would never want to get close to 200psi. What I am asking is what possible downside (other than a harsh ride) is there to running at the max listed on the sidewall.
Quote:
Originally Posted by CapriRacer
Sorry, but the DOT adopts the existing tire standards whatever they might be - not the other way around.
|
Its hard to read legislative text, but the way I read this, it sure looks like TRA sets the max inflation standard, not DOT:
Part 571.139: Standard No. 139; New pneumatic radial tires for light vehicles. - Federal Motor Carrier Safety Administration
Quote:
Originally Posted by CapriRacer
The modern DOT regulations date from 1968 with recent updates. But they reference back to the tire standards like the page above.
So here is a page that explains where those numbers come from:
What you are looking for is the last thing on the page.
|
ok, 1968.
I don't think anything you wrote really contradicts what I wrote.
That page doesn't explain what those numbers are based on, it just lists them.
Where did the Tire and Rim association come up with them from in the first place?
I realize cars are only tested at the recommended pressure. Cars are also tested without grill blocks or underbelly panels or boattails or power steering deletes. The whole point of this website is that we as owners don't always agree with the manufacturers decision when it comes to the balance of comfort vs efficiency.
And what I am saying it that the doorjam recommended pressure is based on ride comfort.
Every source I can find says that low pressure causes a myriad of safety concerns, while there are no substantiated safety concerns of running at the listed maximum.
You say the max is meant "only for certain conditions" but where are you getting that information from? If running at max pressure was actually dangerous on anything but the track as you are implying, wouldn't we expect to see a warning in the tire manufacturers literature?
Like you said, they don't test the tires above the listed pressure (they do test them below, they are required to, to simulate real world conditions), so on what basis can anyone say that going above doesn't improve performance, safety, longevity, or efficiency?
Given that: Tire wear, braking, handling, hydroplaning, and potential for overheat induced tire damage and blow outs, all get worse the lower pressure is below the pressure listed on the tire sidewall, and all improve as it rises back toward it, it seems there should be some concrete and specific concern before choosing to inflate them to anything less.