Tires PSI - Is it by car or by tire?


#1

Should I fill the cars tires by the tires PSI rating or the cars PSI rating? I had a Prius before and in the Door panel, it had the car’s PSI rating which is what I used.


#2

Use the car’s psi rating on the door panel.
The tires you have on your car are used on many different vehicles, and often use different psi values for different vehicles.


#3

the PSI is by the car. The PSI on the tire is the max PSI you can put into the tire safely. The tire can go on many different cars so the tire PSI isn’t car specific. The PSI given on the door sticker, and owner’s manual is specific for the car and that’s what you go by.


#4

I usually set mine a couple of lbs higher then the door sticker.

The tire pressure on the side of the tire is the MAX pressure. And you’ll notice it also has the weight associated with it. Many tires with the same brand and size will fit multiple vehicles. Each vehicle may weigh differently…so they’d all have a different optimal PSI setting.


#5

What they said. Make sure you measure the pressure ‘cold’, before you drive the car that day. And use a high quality dial or digital gauge.


#6

What everyone else said is correct. However, in the interest of improving fuel economy many people go 4-5 psi above recommended tire pressure. You’ll gain a little mileage and lose a little comfort.


#7

Use the car’s PSI rating.

If you choose to go above it, you risk things like suspension damage and tread separation. I’d hate to have a warranty claim for replacement struts denied because I didn’t adhere to the car’s specifications.


#8

Never use the PSI rating on the tire. Always use the vehicle PSI rating as others have already said. The PSI rating on the tire is a numbskull idea that the government came up with.


#9

Of course, the specifications on the door are assuming that the correct tires are mounted on OE or equivalent wheels.


#10

within reason, i think it is ok to go 4-5psi. I don’t feel there can be damage to suspension or anything else.


#11

missileman wrote:
The PSI rating on the tire is a numbskull idea that the government came up with.

I don’t understand your position here. If the tire manufacturer knows that the tire is not safe when inflated past a certain point, why is it a bad idea to print that limit on the tire?


#12

Over inflating a tire can split the wheel. Wheels are built to handle the maximum pressure of the tires recommended for installation by the car/truck’s manufacturer.

There are a great many possible problems that can arise when tires are under or over inflated. And the maximum pressure on the tire is there as the absolute maximum pressure that the tire can handle when servicing it. To expand the tire’s beads out onto the rim, inflating to the maximum is often needed to get it fully seated even when the rim is lubricated. And many cars are shipped with maximum pressure in the tires. Brightly colored caps on the valve stems indicate that the pressure needs to be checked.


#13

Just using the door panel recommendations is perfectly adaquate, especially if you drive normally which means with lighter loads. Adding a few extra pounds when tripping with the heavier loads of more passengers is more important then worrying about a static tire pressure you use all the time. Running a little higher is worthwhile if you often load your car and it’s inconvenient for you to change pressures. Remember too, that once you start driving, this and weather changes will alter pressures. The import thing is, the pressures are all the same and being within a few pounds on the plus side is no big deal.

. Just remember though, many, many drivers are numb skulls when keeping up with and monitoring their tire pressure and need a little reminder that if a little more is good, a lot more is not necessarily better when it comes to adding air. The pressures on the side wall can be maximum or that used to support the maximum load rating of the tire. The actual load on the tire on a particular car can be much different and the pressure is more in line with that on the door. They are not contradictory numbers so I have to disagree that it is a " numb skull " idea. It’s just valuable, additional information.


#14

In the old days, nothing was written on the sidewall of tires relative to the max load and max inflation pressure. So when tire regulations were introduced in the 1960’s, the regulations required a max load and a max inflation pressure be stamped on the tire so consumers would be informed. At the time, it was common for vehicle manufacturer to use the smallest tire possible - so the vehicle tire placard and the max pressure on the sidewall were the same.

But times have changed and it is now common practice for vehicle manufacturers to use tires significantly larger than the minimum - and the vehicle tire placard reflects that. The pressure listed on the tire does not.


#15

But sometimes you have to use your own better logic when buying replacement tires.
Even the label gets it wrong sometimes … remember the Ford / Firestone / Explorer tire fiasco ?
The door label said something stupid like 22 psi ! And therein was the root cause of all the blowouts…the 32 psi tires could’t take the excessive heat buildup from the added flex of merely 22psi.
-logic ? - On both of my Explorers, 91 & 92, I NEVER…NEVER had any tire issues because I NEVER had merely 22psi ! Always had them at 32psi … wore out one set and bought a second before the recall.
After the recall they put on BFG all-terrain T/A which had a sidewall max listed at 55psi.
aired again at 32psi
– logic people…logic .


#16

@kengreen

I can’t totally agree with you

Let’s face facts: not all car drives understand cars like we do

You can’t really fault a car driver for inflating a tire as per the sticker on the door jamb

Is the car driver supposed to distrust everything the car manufacturer says?

As far as logic goes, inflating those tires to 32psi was logical to you, who understands cars

It might not have been logical for someone who doesn’t understand cars


#17

@lion9car…I think it’s a numbskull idea because drivers commonly over-inflate their tires because the max pressure is listed on the tires. We did just fine for nearly a hundred years with no max rating printed on the outside of the tire. A better idea would be to put a “code” on each tire to let the professionals know the tire limits. The public, in general, has no need to know what the tire pressure limits are…all they need to know is where to find the placard on their own vehicles.


#18
We did just fine for nearly a hundred years with no max rating printed on the outside of the tire.

And before the Max Tire printed on the side…we had full service gas stations that checked the tire pressure for you.

I’m not saying the Max Tire printed is a good idea or a bad idea…Just that there are other reasons why people over or under inflate their tires. I suspect the there would be just as many 30 years ago over or under inflating their tires if 99% of gas stations were self serve like they are today.


#19

Thanks everyone for a lot of good info.

Can anyone confirm that this is the correct PSI rating for a 2000 corolla (P175/65R14) stock wheels:
30 PSI front
30 PSI rear

Both Goodyear specs and drivegreen specs listed the above as the correct PSI rating for the corolla. I checked the Door Jamb (both sides) and it did not have the PSI ratings which is weird. It had the tire size and type but not the PSI.

This sounds low to me. Is it normal for both front and rear be the same rating?


#20

@missleman
"the public has no need to know the limits of the tire "
I think I know what you mean as far as the less then average joker is concerned, but the tire manufacturer does not have the final say on what tires are mounted on what cars. It seems very reasonable as a CYA that manufacturers put maximum inflation pressures and maximum loads on ALL their tires. Some tires have very narrow load ranges and increasing inflation with a heavy load on a cold day in late spring which everyone would agree is reasonable, can be problematic if you don’t check it a few weeks later during a heat wave. My conservative 35 psi can easily approach max inflation, blow the tire off the rim pressures if you don’t check them regularly. I constantly have to monitor the tire pressures on the dump trucks, tractors and yes SUV I drive when swapping off heavy loads for driving comfort…I think I’m part of the normal driving public in general otherwise and I am thankful to have the maximum loads and pressures on all the tires I deal with…even my bike tires. All pneumatic tires are in need of them.

Not knowing the limits for anything whether it be tire pressures or loading your car is an accident waiting/ begging to happen.