tire pressure now 40 psi

Every auto shop seems to be putting 40 psi not like 32psi like back in the day no matter what tire its is, Is this due to better gas mileage or maybe keeping aluminum rims sealed better due to all the bead leaks? does anyone know why?

There are many more forms of auto tires than in previous years. The general rule of thumb most shops go by is 5 pounds lower then the max pressure rating.

most of your newer vehicles will post the man. suggested tire pressure for front and back tires on a label, usually located on the drivers inside door panel.

Silky Shagsalot said:

most of your newer vehicles will post the man. suggested tire pressure for front and back tires on a label, usually located on the drivers inside door panel.

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You should go by whats writen on the tire it's self, The tags are for factory vechiles , so a new set off tires can have different rattings

I keep my psi on the high side to save fuel (about 3-5 over on tires that are susposto have 45-50)

Keeping your pressure up is about the simplest way to save significant fuel

Most modern tires have a higher ratting than years back , Likely just modern matterials and newer fuel efficany standards

Many tire shops will only fill the tire up with as low a psi as possible for insurance reasons , many of the larger shops will even have 2 different air lines a regulated pre-set, so all they have to do is clip on without worying about metering the pressure or over filling

Silky Shagsalot said:

most of your newer vehicles will post the man. suggested tire pressure for front and back tires on a label, usually located on the drivers inside door panel.

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This is the correct answer as proper inflation pressure is dependent on weight of vehicle. Anything other than that may cause an alteration of safe handling, braking or tire wear characteristics. Car and tire manufacturers work together to determine optimal benchmarks. (I always tell the repair shop/dealership to inflate to pressure on door jamb if I have tire work done and then check when I get home) They are not doing you a service by overinflation.

from Goodyear.com:
"To find the proper air pressure for your tires, look in your vehicle's owner's manual, on the sticker on the driver's side doorjamb, or in the glove box".

from Michelin.com
"Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall."

BarnBuster said:

from Michelin.com
"Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall."

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They base those numbers around...? Driving on a smooth oval track with a load of one driver at 80kg?

As can be seen, if tire pressure is increased, the surface area of the tires to ground will decrease in response.
This reduces friction and--to an extent--the handling ability of the vehicle.
Now, place a stereotypical fatass Yankee Doodle in the car and once again, the pressure changes (along with loads on the shocks and springs).
So considering the dynamic variables, WTF does the tire company know? I imagine they say to go with the car door value because it is a "safe" level which allows for plenty of headroom in the event of overloading. But this does not imply an optimum for one's environment.
Furthermore, if the tire profile is changed to low-wall (and fat spinner rims) then the dynamics change remarkably. The door number won't help very much there, will it?

Variables to consider:

• Temperature
• Elevation (i.e. Atmospheric Pressure)
• Load
• Road Surface
• Tire Profile

I'm sure there are more...

Green cars, you wanna keep on the high side, mostly teens that like spinning them.

Blue cars you keep lower, mostly women with shopping in the trunk that drive fast and need a good hook.

White cars, generally have more HP and rip em off the wheel anyway so what you put in wont be there long now, Will it ?

Police cars, over inflate. That way when he`s chasing you and hits a pot hole...pop goes the tire, snap goes the linkage, down goes the nose and suddenly he`s taking a right.....