Ok, we all know that we're supposed to follow our vehicle's placard for recommended tire pressure.

Fine. But there's an issue with tires in general that I believe NEEDS to be addressed but I've never seen any info about whatsoever.

To wit: My Lincoln Mark VIII says front & rear tires are to be 30 PSI. Easy enough.

But here's the issue:

This car came with Goodyears that had a MAXIMUM pressure rating of 35 psi.

The Firestone's I have on it now, same size and all, have a maximum pressure rating of 44 psi.

I don't know how many of you have actually 'felt up' various tires, but I have--and 44 psi rated tires have noticibly flimsy-er sidewalls than 35 psi rated tires...

Ergo---when I put 30 pounds of air in these Firestones, they look--and feel-- FLAT. And I AM wearing the outsides of the tires out faster than the middles, which of course is indicative of not enough air pressure!

I can find no info about adjusting "recommended" tire pressure based on the tires actual rating.

SO, if anyone HAS any info, I'm all ears!

In the meantime, I'm going to do an experiment with what's left of my tires...

My 30 psi rating is 86% of the factory tire's 35 psi max, but only 68% of the Firestone's 44 psi max. But 86% of 44 is 38 psi, and THAT'S what I'm going to start running in these tires. I'll bet the whole car feels better to drive, and they'll probably wear better. We'll see!

Any opinions on this?

Sounds reasonable to me.

You bring a good point and the different constructions and how that would impact the air pressure.

Sorry I can't help. But I must say, I've never "felt up" a tire before... you really had me laughing on that one.

I've always run my Firestones at 35-40 PSI but recently for fuel efficiency inflated them to the 44 max.

I honestly don't like them fully inflated as obviously the ride is harder and the steering on my wife's Trailblazer feels too light at speed.

I was told by the guy at Costco to follow the tire's recommended PSI on the sidewall for max performance. The door placard is for factory tires, replaced by the same brand/model. I've also read this on the RV board I frequent as well..

If you put the full 44 max pressure in at 'cold', you'll over inflate when they get warm increasing the hard ride quality. He said the best pressure is about 2-4 lbs less than tire placard at cold. He also recommended a digital tireguage for accuracy, and in hot weather, check every 2 weeks and reinflate as necessary for max MPG. Tires lose about a pound of pressure a month.

Our Jeep has an onboard tire pressure monitor. Not sure how accurate it is, but it tells me if they need air or not, so I CAN be accurate!

Tire pressure recommendations are always a compromise between ride comfort, fuel economy, traction, handling and noise.

Lower pressure generally gives you better ride and traction, but handling and fuel economy suffers.

Higher pressure gives you better economy and handling, but traction and comfort can suffer.

Noise can vary from tire to tire, depending on tread pattern and rubber composition.

Your Lincoln is probably weighted toward ride comfort - while sacrificing some handling and fuel economy. I'd say go ahead with the 38 PSI - but remember you will lose some wet traction and be prepared for it.

Think you have the right idea about raising the pressure.

+1 on starting at 38.

I agree with Nu2, door placard refers to factory setup. I think the tire wear is a HUGE indication that the tires need more air.

I run mine at the cold air recommendation on the door placard. 32psi on the Pilot, 35psi on the RAM. Now, the boat I keep at max cold, which is 50psi. Question, I have a single axle, and the tires look as if they need to be rotated looking at the wear pattern. Does anyone here rotate their trailer tires? They are wearing as in steps on the outside.

If they're standard bias ply it shouldn't hurt to rotate. On radials, I've been told not to change the rotation direction as it could lead to sidewall failure. Someone here with more knowledge may chime in differently tho...

Rotate radials front to back only. Keep them on the same side of the trailer.

Tires should be inflated to manufacturers recomendations, ignore the door placard if different tires than stock.

Have your tires inflated with nitrogen. They will not build up air pressure from temp changes.

So what do you do if the max tire pressure on OEM-supplied tire says 44 psi and the door placard says to inflate to 32?

Also, with TPM systems with individual pressure transducers, you won't be able to go above or below the factory recommendation much without tripping a light.

Seems like he is giving conflicting advice.

here's an old rally racers trick...use chalk to draw a line across the tread of the tire. Draw the line on each tire, then drive the vehicle. If the chalk line wears in unevenly in the center then you're overinflating that tire. If the edges wear first, then youre underinflating. Its best to err on the overinflated side-but this method should allow you to figure out the correct pressures for the combined unique attributes of your vehicle, the tyre design and how you actually drive the car

When I was younger I raced radio controlled cars on hard packed dirt oval tracks. We did that with whiteout to see the wear pattern and make adjustments from there.

My wife's Caddy's OEM Michelins say max tire pressure 44 psi.

The door placard states something much less.

Tires at MAX PSI often do not get good fuel economy. Try in the 85-90% range. Or so I have heard/been told.

I put 38 psi in the tires this morning finally (been driving the bike & truck lately)...

man, shoulda done that a LONG time ago. Feels like I got brand new power steering, the car doesn't feel as squishy, just feels better. BUT...the ride DID get a bit firmer, but I guess there's always a compromise!

I reset my average mpg meter again. I reset it when I cleaned the MAF sensor about 2 months ago, old mpg was 17.6, this morning was 22.4, pretty good gain. BUT, it USED to be in the 25's, so I'm interested to see if running on tires with air in 'em helps!

For tire pressures, ALWAYS go with the indications ON THE TIRE. The car's advice is only sound as long as the exact same brand and model tire as original is still on the car. Use anything else, follow the tire's inflation instructions.

Tire "maximum pressures" are supposed to be measured cold. A tire with a maximum inflation pressure of 44psi COLD is NOT overinflated if you measure it hot and it registers 50PSI. Pressure increase is well understood and is accounted for in the tire's recomended COLD tire pressure.

Also, if your tire(s) look(s) low, and you measure it, and the gauge readds 25psi (for discussion), and you normally run 30psi, but the air source (gas station) is 10 miles away, proper procedure is to save the pressure reading, noting you want 5psi added.
Drive to the air source, re-check tire pressure, which is now 29PSI, and inflate to 34psi (adding the 5 it was low).
When cold again, it should register very close to your desired 30psi.

And thus you are screwed into having to buy the original tires, or living with fault codes.

Lowrider,

I couldn't disagree more on your perception of tire pressures. Where are you getting your info from?

Again, max tire pressures as stated on the tire are only there so stupid people don't inflate them to 100 psi.

Each vehicle manufacturer determines what is best for each vehicle, regardless of who's tire is on the vehicle.

Again, on my wife's 08 Caddy, for example, the OEM-equipped Michelin Pilots state that the max tire pressure is 44 psi. Cadillac wants them to be set at 35 psi. This situation plays out over every car/light truck that I've ever seen. Put another way, I've NEVER seen a door placard that states to inflate a tire to its maximum limit. For most passenger car/light truck tires that I've seen, that max pressure is usually 38 or 44 psi.

It baffles me how so many people think they can re-engineer their car better than a team of highly-educated engineering teams that have ambulance-chasing lawyers waiting for their opportunity.

Well... some would point to things like this.

http://www.boatingabc.com/forums/ubbthreads.php/topics/414645/1/Love_My_Civic_But.html
http://www.boatingabc.com/forums/ubbthreads.php/topics/419345/Flushing_DexCool.html#Post419345

It's not apples to apples, but some of those engineers have given us some pretty good reasons to question them.

Mike,
Don't confuse the bean-counters with safety engineering.

I have seen many other models with stone holes in condensers.

LOL - I know what you mean. I generally agree that the more complex cars become, the more (unfortunately) we need to stick to what the engineers say. The problem I see is that to the end user, it's often unclear whether the breakdown was in engineering or bean counting, because they unfortunately are no longer independent departments. All they know is, they just dropped $35K on what is supposed to be one of the most state of the art vehicles made, and a month later their entire A/C system has to be replaced at their expense.

Condensers have been "hangin' out" for a great many years and any car can take the hit - but this crop of late model Hondas is suffering an epidemic of them.

Not to wander too far, but anyone with an 01 M/B E320 best not spill any beverage around the center console cupholder. It WILL ruin your Transmission Control Module (which conveniently hides below it out of sight), which WILL ruin your day, to the tune of about $1K....

Yep, there's a GREAT example.