Tire pressure for 31s? Same width means same pressure?
- Thread starter SSTJ
- Start date
Vtx531
TJ Addict
Funny...they get their calculations from the Tire and Rim Association....the same guys that also say no lower than door placard pressure.
Their recommendations for door pressure guidelines assumes you are staying with OE tire sizes.
If you remember the Firestone/Ford debacle from back in the 90s, the tire itself turned out to not be the problem, it was the low tire pressure that ford engineers recommended for the Explorer (also Mazda) that caused the problem. Granted the passenger rated Firestone Wilderness A/T wasn't all that great of a tire in the first place, but it was not uncommon to see people with completely worn out tires that fell under the recall come in to get their free tires.
Those air pressures are ONLY for the various sizes of factory-size tires listed on the placard on the door jamb. Once you go up in size like to 31, 32, 33, or 35" the correct air pressures will be lower than what is on the factory placard.
Vtx531
TJ Addict
Negative, that is for changing tire size from factory - larger or smaller.
That doesn't even make sense, if you changed to a factory size tire there would be no need to figure out a new pressure.
No it's not! It is specific to the tires that are on the sticker. Factory actually recommends not going outside of those tire parameters...
Vtx531
TJ Addict
When you go to 40's, you dont give a fuck about safety, handling, steering, scrub radius, vibration, gas mileage, rollover tendency, spring rate, tire wear- so run whatever makes you feel warm and fuzzy inside. You are so outside the designed vehicle dynamics for driving on the road it doesn't matter.
Why wouldn’t I? Scrub radius is planned and I plan to be able to daily drive it. I’d rather not roll over, hate vibration and need it to be well handling.
What's funny is you stated this earlier
Yet you refute their recommendations of 22 psi??? What makes you smarter than the T&R Association, to tell him to run no less than 29 psi? Also "or higher if required"??? Really?? So you're suggesting that I go higher then the 80 PSI that is recommended on my truck if I want to haul more weight?
The tire pressures listed on stickers on cars are for max load capacity for the vehicle with the tires it came with and nothing else.
Oh you mean people such as yourself.
When I mentioned going with the 22 PSI recommended it was a starting point for the method I suggested to find out the optimum tire pressure to achieve the best possible contact patch. Which will insure there is more than enough air in the tire to keep from generating excessive heat from running under inflated.
ONLY for the SPECIFIC tire sizes shown on the placard. Those tire pressures are not correct for anything any bigger or smaller than what's on the placard.
Vtx531
TJ Addict
Why does Jeep specify 33 psi for stock tires? The load capacity for P215-75R15 is 1690lbs. (x4)
Does a TJ have a 6760lb gvwr?
Why does Jeep specify 29psi for factory LT 30-9.50R15? That is a load capacity of 1,376lb each. Totally different load capacity than the P-tires for the exact same vehicle. hmmmm weird...
Maybe there are other factors besides load carrying capacity that go into deciding the "best" tire pressure.
Have a nice evening, merry Christmas, god bless America
Does a TJ have a 6760lb gvwr?
Why does Jeep specify 29psi for factory LT 30-9.50R15? That is a load capacity of 1,376lb each. Totally different load capacity than the P-tires for the exact same vehicle. hmmmm weird...
Maybe there are other factors besides load carrying capacity that go into deciding the "best" tire pressure.
Have a nice evening, merry Christmas, god bless America
It doesn't effing matter how or why Jeep engineering in combination with the tire suppliers came up with those recommended tire pressures. That's what they officially recommend, don't be trying to come up with your own tire pressures you think are more correct than theirs based on their load ratings. The same exact tire will have different correct air pressures depending on the vehicle weight and type.
Vtx531
TJ Addict
There is a note on their tables that say something similar to "no lower than placard pressure". It's that simple.
If you go to an upsized wheel with same overall tire diameter (as is a common trend on many vehicles) there is less tire air volume and the required pressure may be higher than what the placard calls for. In that case, it would be more important to not overheat and blow up the tires, even if you are sacrificing all the other design criteria by running a higher pressure.
Vtx531
TJ Addict
Vtx531
TJ Addict
It is so simple. Hilarious.
The pressure to carry the vehicle weight is a MINIMUM. Not the ideal/best/recommended pressure.
MINIMUM. Nothing more, nothing less. So easy a caveman can do it.
Minimum?? You're ignorance is astounding....
So 80 psi, is on what's indicated on my trucks, by your accounting I should put more pressure in my tires if I plan on hauling more weight and I should never have less than that pressure under any circumstances?
SMH... Not only is that wrong it's completely idiotic!
You are back and forth all over the place and very little, if any of the things you have said is relevant let alone accurate.
Vtx531
TJ Addict
Reading comprehension is hard for some people like you
I bet you put in 20 psi to your truck and I see you on the side of the road with blown tires and then complaining about tire quality.
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