Hi Guys,
Ive been reading posts about tire pressures anywhere from 44psi to 49psi. Im going to inflate mine today but am wondering if tire pressures should be changed seasonally? We are in the high 20'sF to mid 50's F now. If anyone could tell me what PSI to go to, I would appreciate it.
Thanks,
Anne

 

I inflate mine at 44 psi, and check them monthly (my wife drives the car, otherwise I would check them more often).

A good rule of thumb is that a 10 degree move in temperature will move the air pressure by 1 psi. So, if you check your tires on a 50 degree day, and they read 44, they will be about 41 on a 20 degree day.

Does this help?

 

I have been putting 50 psi in my original tires for some years now (I have my own tire mounting and balance equip). and got good wear patters even at 56K. I placed some new 175x65x14 (898 rev/mile) I have lost mileage even with the 4.99% overall gain, and a 2.4% net gain on the odometer check against milemarkers.

Bill Campbell

 

I check around the first of the month (I also dust/clean and whatnot), and keep them at 45 PSI.

 

How much of a MPG gain is everyone seeing? The max pressure on the factory tires is rated to 44. I'm not sure I'd risk going above that for a few MPG.

Is it dangerous? I mean.... one of the main reasons behind all those Firestone problems was people running them LOW on pressure to "improve the ride." Mind you there seemed to be a tire issue too because Goodyears didn't fail at the same rate. Now, admittedly thats low pressure not high, but with that kind of background... I'm not sure I'd be comfortable tinkering with my reccommended tire pressures, especially beyond the MAX. It might all seem fine until some day.... things go very wrong.

Also from what I've read high pressures will make the handling worse because they reduce the contact area of the tire with the road.

 

Ford says 3 MPG change for 10 psi change.

50psi causes virtually ZERO increased chance of blowout, and DOES significantly improve tire life ( reduces wear overall ) and DOES give about 4 MPG more. Over the long haul, 4 MPG adds up, and the extra 20,000 miles of tire life works for me.

50 psi DOES decrease contact area with the road by one-third.
This DOES NOT MATTER on dry pavement conditions.
( The contact area is still pretty darn good, 80 sq. inches at 50 psi )
This DOES matter quite a bit in wet, or icy conditions.

The way I see it, I don't usually carry an air compressor around with me, but I always carry my index finger with me.

I inflate to 49 or 50 psi when at a service station.
I live in an arid climate.
On those RARE DAYS ( like 5x a year ) I use my finger to let out 10 PSI on rainy days.... for the rest of the time, I reap the benefits of 50 psi.

Ask yourself if the decreased contact patch with the road is a disadvantage for you. ( do you take corners fast, and in adverse weather frequently? )


Cheers!
-John

 

It should also be noted that the tire sidewall says 44psi Max. Pressure.
It is a recommendation of most tire manufacturers to add just 5psi more when heavily loaded, or if you do mostly high-speed highway driving.

So 40psi is safe by all accounts, and you will not see any harmful effects at this pressure.

It was pointed out to me that going up and beyond 40 psi may make the tire so firm infact, that more bumps and vibrations may be transfered to the vehicle and may reduce the life of wheel bearings and bushings.

 

Wow.

Any posts about recommending over-inflating the tires seems kind of scary to me. Every tire manufaturer's website I've visited recommends inflating the tires to the VEHICLE MANUFACTURER'S pressure, and not to the maximum pressure on the sidewall. The same goes for the owner guide.


The part that really scares me is when people make statements like:

"This DOES NOT MATTER on dry pavement conditions. (The contact area is still pretty darn good, 80 sq. inches at 50 psi )".

Is it reasonable to assume that the handling of your vehicle is reduced by a similar amount during emergency (accident avoidance) maneuvers?


Is it really worth putting your family's safety at risk just for a couple of tenths of a MPG (at best) just for bragging rights? Also, won't the increase in tire wear in the center of the tire mopre than offset any savings in fuel economy?

Maximum MPG is fine and it's great to acheive the best we can, but I don't think it's necessarily worth the compromises suggested here.

 

Statements like "Ford says 3 MPG change for 10 psi change" sounds a little misleading to me. I'm sure that's true to a point (probably when starting at lower pressures) but that the benefit decreases as the tire pressure increases.

 

California Highway Patrol routinely runs 40+ lbs in their cruisers, especially in the rain. Stops hydroplaning, eliminates chances of rolling a tire off the rim in a hard corner or slide, improves directional stability and so forth.

LOW pressure is very, very dangerous, as it gives room for sidewall squirm and for the tire to roll right off the rim.