Tires: Tire Inflation, tire placard, tire inflation

Question
Do recommend to go with the car manufacturer' reccommendation or the tire manufacturer's reccommendation  

Answer
JJordan,

On every vehicle sold in the US, there is a sticker – commonly called the tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

That would be the car manufacturer's recommendation for the original tire size.  If you are using a different tire size than what is on the placard, then the pressure has to be recalculated.  The calculation is not difficult but it requires the use of tire load tables which are not allowed to be published on the 'net.  But I happen to have a copy of them and can do the calculation if you need it.

So what would be the tire manufacturer's recommendation?  Is it on the sidewall?  No, that says "Max" and that's what it means - the maximum pressure to be used for that tire.

What do the tire manufacturer's recommend?  If you carefully check each tire manufacturer's web site, you'll find they all recommend following the car manufacturer's recommendation.

But personally, I like a car that handles crisply. So I use 3 to 5 psi above the placard pressure.  I also get better fuel economy, better wet traction, better snow traction, better tire durability, better tire wear, but I do have a degradation in ride harshness (but I am willing to put up with it.)