Tire pressure


sailor86
01-01-2012, 10:51 AM
The sticker on the inside jamb of my driver's door states that front tires be pressurized to 32 psi or so. But when I checked what my newly installed tire had, it was 44 psi, as per the tire etching itself. Tell me if I'm correct, but I should follow the car's sticker specs over reading the tire itself, right?

MagicRat
01-01-2012, 09:30 PM
Follow the specs written on the sticker on the door jamb. It is a general guideline for tire pressure as determined by Mitsu engineers for the average Gallant with an average load under average use.

The pressure written on the tire is the recommended pressure for the maximum weight that the tire can handle. If you are carrying less than the maximum weight then the ideal pressure will be lower.

For example, the tire sidewall may say something like "MAX LOAD 1500 LBS AT 44 PSI". This means that the tire needs 44 psi to retain the ideal shape and contact patch at that maximum load.

However, your car, with an average load (ie:2 or 3 people plus some luggage) may only place approx. 950 lbs on each tire. Therefore you only need 32 psi to achieve the ideal tire shape and contact patch.

You can take this one step further. If you load your car to the maximum capacity, say 4 or 5 big people plus a trunk-full of luggage for a long trip then its reasonable to put extra air in the tires, to boost the pressure to approx. say 35 to 38 psi. But for normal use, use the sticker's recommendation.

CapriRacer
01-02-2012, 08:38 AM
While MagicRat got the right answer, unfortunately he got some of the details wrong.

First, what is written on the sidewall of the tire is typically a MAXIMUM. It will say something like "Max Load XXXX, Max Pressure YY". However it might say "Max Load XXXX at YY pressure" This indicates a relationship, but it doesn't mean that this is what should be used when the vehicle is fully loaded - it's an indication of the realtionship for the TIRE!

Further, what is listed on the vehicle tire placard (the sticker mentioned) is for a fully loaded vehicle (unless it states otherwise). If the placard doesn't have any exceptions or explanations, the pressure listed there should be used as stated.

amy@af
01-02-2012, 11:49 AM
interesting topic. thanks guys, I'm putting a link on our face book page :thumbsup:

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