Tires: Tire Pressure, shelly shelly, winter tires

Question
Hello Barry,

I recently bought a car and they put brand new winter tires on it.  The tire pressure on the inside panel says 34 however my gauge reads that all the tires are about 30.  Does this often happen?  Do tires usually get installed at a lower pressure or lose pressure that soon? It's only been about a month.  I want to know if I should be concerned about these tires losing pressure.

The other point is, my father thinks that your tire pressure should be a little lower than the one you are shown on the panel of the car.  Does that make sense or should I always try to keep the tires at about 34?  Thanks for your help,
Shelly  

Answer
Shelly,

There are lots of reasons why tire pressures would not be what is on the vehicle tire placard, so it's impossible to say which one is at work here.

But let me give you some guidelines:

If the tire size is the same as what is on the vehicle tire placard, then the pressure ought to be the same.  If not, then the pressure has to be recalculated.  But in order to do that we need to know what the placard says for tire size and pressure, and then what the new tire size is.

You should also be aware that outside temperature will change the actual reading - about 1 psi for every 10°F.   HOWEVER, the tire's pressure is supposed to be set according to the current outside temperature, so, in theory, it would have to be adjusted every day.

But let's be reasonable.  When it's cold outside, no one wants to be playing with tire pressures.  So set the tires to the coldest expected temperature the whole time between checks - compensating for the 10° rule!

I am sorry to disagree with your father, but I would consider the pressure on the placard to be a MINIMUM.