Hyperinflating tires

[CapriRacer]

Originally Posted by JSH

My guess is the transporter is pumping up the tires to reduce the amount of movement during transportation.

I can confirm that many vehicle manufacturers put in up to 60 psi in the factory. The transporter isn't supposed to be adjusting pressures.

[teoman]

Also higher pressure is recommended for storage, I think.

[Tahoe_Hybrid]

Originally Posted by CapriRacer

I'm starting a discussion thread here - and I'm hoping to move a discussion that got started when I introduced myself:

http://www.ecomodder.com/forum/showt...ires-2522.html

So hopefully this will be a bit more visible and a bit more "on topic".

First, let's define some terms:

Underinflation: Using less inflation pressure than is listed on the vehicle placard (assuming the placard tire size is being used.)

Overinflation: Using more inflation pressure than is listed on the vehicle placard (assuming the placard tire size is being used.)

Hyperinflation: Using more inflation pressure than the maximum listed on the tire sidewall.

Vehicle placard: The sticker on the vehicle that lists the original tire size and the proper inflation pressure for that size.

Agree?

Any other terms we need to define?

Don't do it buy a tire that is rated higher you can buy passenger tires rated to 51PSI


Falken ZE950/G4 pro
Goodyear Assurance CS Fuel Max are a few known tires

[CapriRacer]

Originally Posted by Tahoe_Hybrid

Don't do it buy a tire that is rated higher you can buy passenger tires rated to 51PSI …...

You are mistaken if you think that because a tire has a higher max pressure, it is somehow better. That's sometimes true, but not always, and in particular, for passenger car tires, it's mostly not true.

Why do I think that? Because tires are tested at the rating point - at the max load and its corresponding pressure (with a couple of exceptions.)

For Standard Load passenger car tires, that pressure is 35 psi, except for tires done completely in metric units where it is 36 psi (2.5 bar, 250 kPa) For Extra Load Passenger car tires, the pressure that corresponds to the max load is 41 psi (2.8 bar. 280 kPa)

So one would be correct to say that an Extra Load Passenger car tire is stronger than a Standard Load Passenger car tire - but that's because an XL is rated at a higher load.

Further, a LR E LT tire (rated at 80 psi), would be stronger than a Load Range C (50 psi), but, again, that's because the max load is higher.

But a Standard Load passenger car tire can only be labeled with a max pressure of 3 pressures - 35 psi (36 for metric), 44, and 51 psi.

And a little wrinkle in this: The speed rating test for H rated tires requires a pressure of 44 psi and for V and higher speed ratings, its 51 psi - So an H rated tire will either be labeled with a max pressure of 44 psi or 51 psi, but a V or higher rated tires can only have 51 psi max pressure.

The pressure for t and lower speed rated tires is 35 psi (even for the speed rating test), so a T and lower speed rated SL tire will be labeled with a max pressure of 35, 44 or 51 psi. That choice is arbitrary.

So why are the static burst pressures for passenger car tires over 100 psi? Because the structure of a tire is all about fatigue resistance - and to get it, the strength of a plies and belts has to be multiple times what is needed for the rated pressure. The principle is described here: https://en.wikipedia.org/wiki/Fatigue_(material)

Hope this helps clear things up.

[royanddoreen]

Originally Posted by gumby79

Attachment 19806
4.5" skid mark left by a 7 .5" wide tread 235mm section ÷ 25.4 =9.25" tire inflated to 80 psi with only 2500 pound on the axel.
Notice there are three primary stripes Center and on the edges there are two 1/4-0"wide strips. These two 1/4-0" wide strips are the portion of the tire which contains studs which gave me traction on ice
Also notice, section width does not equal tread width. Section width is the widest point of the sidewall measured on the specified test wheel for that tire size. And this amount of variance varies with tire size make model manufacturer wheel that is mounted on ECT ECT...

This should tell us all that high pressures to acheive max mpg #'s are not worth it. There is a best psi which gives us max traction for accident avoidance.

[Galvatron1]

Originally Posted by PaleMelanesian

Just last month, I informally tested 55 vs 60 psi. There's a certain long but gentle downhill on my commute, about 1/2 mile long. 55 psi would just maintain speed at 40mph, while 60 psi would gain about 5, to 45mph at the bottom.

Wow that's a substantial gain!!

1. What's the sidewall max & type of tire?

2. Anyone else run at 60 psi with similar gains, & no increased tire wear?

[Galvatron1]

Originally Posted by CapriRacer

If the tire has a plug in it, then you shouldn't be inflating the tire over the placard value. Plugs are temporary repairs have have an annoying habit of leaking. Maybe not 100% of the time, and maybe not NOW, but often enough that they are unreliable for anything other than a temporary fix. So get the tire properly repaired - NOW. (which brings me to point #3)

I got a patch a few months ago, are those ok for overinflation or hyperinflation? I've been inflating to 50 psi. I think it leaks a few psi quicker than the other 3 tires.

[CapriRacer]

Originally Posted by Galvatron1

I got a patch a few months ago, are those ok for overinflation or hyperinflation? I've been inflating to 50 psi. I think it leaks a few psi quicker than the other 3 tires.

Some patches are barely adequate for 35 psi, so it depends on what patch is being used and how high you are going. I would watch it very carefully for a bulge. Put it on your schedule to check every month or so. Rub the spot with a GLOVED hand and feel for a bulge. If you detect a bulge, change out the tire immediately - like the same day!

If the patched tire is leaking, that's not a good indication.

[Galvatron1]

I can't feel for it, it's a rear tire. I'll just bring the pressure down to 35 psi, to play it safe.

1. If I bring the patched tire down to 35 psi, do the 3 good tires have to be reduced to 35 psi as well?

2. If the patched tire starts leaking rapidly, do I have to change all 4 tires or just that one?

These OHTSU tires all have lots of tread left. Were installed August.

[teoman]

I would go 35 all round.

You can just replace the one tire.