The sticker on the door is based on Ford's recommendation with the factory tires only for the type of ride they think you want..

Like on Gen 4 Tauruses, it's set at 30, which is absurd. They lowered the PSI to give you a cushier ride. I have my front two tires around 39-40 PSI, and my rears in the upper 30s. Just don't exceed the maximum PSI stamped on the sidewall of the tire.

A higher PSI will give you better mileage, and better tread wear, especially if you put more air in front tires (since more weight up front) versus rear.

 

I run 35psi all around.

 

I do 36psi myself.

 

Just got back from upping them all back to just below 40psi. One had dipped down to 30 and the other three were all hovering at around 32 or so.

Feels like such a different car with the extra 8lbs all around. But unfortunately it also makes you aware of every tiny thing in every small corner of the vehicle that's loose because you can hear it all with every bump in the road.

My two rears can go to 44psi, but my two Douglas tires up front have a maximum of 51! Dare I creep up into the 40s on those?

 

Tier Pr

Upon buying my Taurus, I did all the usual **** including checking tire pressure. And as I'd always done with other cars in the past, I inflated the tires to the recommended psi as listed inside the door, 33psi in this case. And in spite of the fact that I thought they still 'looked' a little low on pressure, I decided to ignore it figuring Ford knew better.

Fast forward a few weeks and I wound up needing a quick tire replacement while on a long haul journey. And because it was a holiday, my only real option was to duck into Wal-Mart.

They fitted my new tire and I drove off. Later that day I decided to do that day's tire pressure check and found that Wal-Mart had inflated all 4 tires to very nearly 40psi. And yeah, they didn't 'look' low on pressure anymore.

My tires are 205-65r15

Is it common to exceed manufacturer-spec psi?

Yes but, they need to be aired cold, like before driving at all.

I added a pic, this is a wheel and tire I got at Pick-A-Part for $5 + a $10 core. It had 40# cold. There is 5/32 tread on outside, between 4 and 5/32 inside and maybe a half in the center, basically well below the wear bars. the tire tells it's own story. Too much pressure.

Different tire designs will wear different, as well as how you drive. I usually go +2 cold and my tires wear even in the center, but usually more to the inside on all locations on my Taurus/Sables and My Lincoln Cont. Past and present.

In cold weather all mine tend to lose maybe 2 to 5 psi per month. Old rule, everything leaks, just depends on how much.

-chart-

 

I use the Ford recommended pressure - 33psi. Maybe slighly higher (34psi), because I know that higher pressure reduces the contact patch with the asphalt. No way I will run them at 40psi... that will decrease the grip and, in a 100F day, the pressure inside might be dangerously high.
What most people don't know is that the cheap tires will have weak construction (side walls) and will look underinflated no matter what. And they will "eat up" gas anyway because of that constant change in tire walls (once per rotation, every part of the side wall will be "squished, eating energy).

Draw an uniform chalk patch on asphalt and drive on it. Then look at the tire to see how much chalk has on it and where.

I just replaced on my wife Sonata the "Kumho" tires (that started to feel glassy on threads). They always looked "low". Installed 4 BFGoodrich ones (they have a rebate) and on the same pressure they look as they should (not low as the others).

Another observation is that initially I thought inflating them with nitorgen is just a scam. But I realized that the pressure inside stays the same on a wider temperature range. Maybe because the humidity (water content) in the pumped air is changing that pressure drastically with the cold weather (when changes phase to water).
Of cours, if you pump the air in Arizona, at 5% humidity is different than if you do it in Virginia at 95% humidity...

 

Water in air



Agree about N2. However, all air compressors with air cooling will have 100% humidity in the storage tank. There is water in there.

I air my own with simple air compressor. Maybe more important is keeping the pressure checked, and correcting any low one. And in doing that, when you find one low compared to the rest, look for leak, and from time to time they leak around the rim. We in the rust belt normally know all about that.

Correct air pr for each person's needs depends on their driving habit, and type of tire. If I'm going to haul a load, I will add several pounds to the rears. Planning a trip in the Lincoln with 5 people, and luggage for 5 days in the trunk. I will add air for that. And that car will adjust the air ride and the car will be quite level. I can still remember my old '72 Colony park wagon that when was laoded caused the head lights to blind squirrels.

-chart-

-chart-

 

I run at 35psi.

 

I can still remember my old '72 Colony park wagon that when was laoded caused the head lights to blind squirrels.

-chart-

I can still remember bias-ply tires, too. It was like Christmas when the factories went to radials

 

DN101, you are checking and adjusting cold, like first thing in the am before driving? Even a few miles, esp. in your climate, will raise the psi considerably preventing an accurate check. Also, what type of douglas tires are you running? All the ones ive seen at wallyworld are 35psi cold max stamped on the sidewall. Just my 2 cents, i would stick to 35-36psi all the way around.

 

Agree, when you load your car seriously, it might need a little more pressure. But not a lot more.
As for leveling - that is a nice feature to have on a new car. Not so nice after 80k miles when you need to replace the air-leveling shocks
In my former antique Renault, headlights had small adjusting levers outside on the side of headlights - for "normal" and "loaded".

 

Air Lift



I had 3 Lincoln Cont '91, '03, '96. All with air over strut and did not have to replace, but I did not go over 95K before trade. The '02 I have now uses a separate air bag that is not part of the suspension in the rear. It uses arms and a conventional spring in the rear. Looks much more durable. Fronts are sturt with spring and looks just like the Taurus system. Last of the breed. In fact, made after they quit taking orders, and made with left over parts, and odd paint colors. Mine Sable Silver, exact same as my '01 Sable. Not my plan, just what was on the lot, new, cheap. All extras no charge, and $5k rebate. Suspension system works great. Now, if I could just get my wife to stop kicking it on hard corners and spinning the wheels against the ABS, the tires would really last. But some things will never happen.-_-

-chart-

 

Hmm. Nevermind, one of my front tires is a General, which is 51psi. the other Douglas is a Extra-Trak II and is 44psi max. They just look nearly identical and since the two tires I replaced outright when I got the car were Douglas as well, I assumed all were.

Which means that after having bought two Firestones from a used yard and then having to replace one of those weeks later with a new Goodyear... I have four totally different tires on the car.

...That's pretty ghetto. But they're all high-tread so I don't know that it makes sense to replace any of them.

And when I added more air last night, I'd driven about 3 miles to get to a fuel station and put the fronts at right about 40psi. I just checked today, cold, and they're showing around 36psi. Interesting.

 

I run mine just above 35.