Tire Pressure

[Holaday1185]

Just a quick question... I recently had all my tires rotated and balanced and my car runs beautifully! A month later I checked all the tires for adequite pressure and filled them up accordingly. I believe my max tire pressure in each tire should be be 77 psi. Is this right? If so, how much air should I put in each tire to get the best gas mileage?

[Alibi]

77 PSI? That seems a bit high for passenger car tires. I've got 35PSI tires now and I've had 45PSI in the past. I don't believe that PSI ratings are odd number either...

You may want to double check that number.

Whatever the PSI is, you want to have that amount of pressure in your tire for maximum life and MPG. Otherwise, the tread will wear unevenly and you'll have to buy new tires a lot sooner than you should have to.

[Holaday1185]

You are right - I spoke before I checked! Each of my tires say not to inflate them over 44 pis. The driver's side front door says to air them up to around 30 to 33psi. Does this sounds correct?

[Alibi]

Go by whatever is written on the tire, but 44 sounds right as long as that is what is on the tire. The 30-33 was probably for the stock tires that GM put on the car.

[volkerc]

i have to diagree, go by what the manual says. mine are filled at 32 all around and i have even wear all across the thread.
if you inflate the tires to 44 psi when they are cold you have already stressed the tire to max, now while you are driving your tires will heat up and build up even more pressure in the tire, already exceeding the 44 psi...

[imidazol97]

Originally Posted by volkerc

i have to diagree, go by what the manual says. mine are filled at 32 all around and i have even wear all across the thread.
if you inflate the tires to 44 psi when they are cold you have already stressed the tire to max, now while you are driving your tires will heat up and build up even more pressure in the tire, already exceeding the 44 psi...

I agree. That sidewall is only a figure rating for maximum load pressure without bursting or something like that. It's been discussed in another discussion online.

The pressure on the door post or glovebox is the typical pressure for the car with typical load. If you carry 6 adults and a trunkful of luggage, I would recommend about 3-4 more pounds cold above the door pressure. I never have gone above 35 psi pressure in my tires. Mine are supposed to be at 30. I usually run at 32 and get even tire wear BECAUSE I rotate my tires at 6-8000 miles. I rotate them myself at home sometimes between visits to the tire store where I had free rotation and rebalancing as part of the tire purchase price.

Carrying higher pressures than 35 on passenger tires is likely to cause center wear or uneven wear on the rears;because of the camber changes on the rears with varying loads they are more susceptible to uneven wear on the edges. It happened to me on 93 LeSabre (tires were already poor and had quality problems from new).

If you want to email me I can refer you to the discussion group about tires where the sidewall pressure has been hashed out a few times.

[Alibi]

Ok.... what I mean is that if a tire is rated at 45 psi you should put in 40-43 psi. If the tire is rated at 35 psi, then put in 30-33. Putting 30-33 psi in a tire rated at 45 because that is what the stock tires were rated at would be the equivalent to putting 20-23 in a tire rated at 35 psi, which would result in uneven wear.

[wrightz28]

err,

ok, put in what the door card says, this is what the manufacturer designed the car around for proper performance and handeling.

Now, the reason why this is there, you build pressure in the tires as you dirve and the air in the tire heats up. Ever wonder why there's so many tires blown apart on the side of the highway? Too much pressure.

[volkerc]

Originally Posted by Alibi

Ok.... what I mean is that if a tire is rated at 45 psi you should put in 40-43 psi. If the tire is rated at 35 psi, then put in 30-33. Putting 30-33 psi in a tire rated at 45 because that is what the stock tires were rated at would be the equivalent to putting 20-23 in a tire rated at 35 psi, which would result in uneven wear.

that sir is nonsense.

[auto trainy]

I totally agree with Volkerc it is nonsense,I dont know where you got that info but its wrong.

[kaspr]

It is important to note that the pressure ratings you see are "max cold tire pressure". So they've accounted for the fact that when you drive, the tires will warm up and pressure will increase. GM's factory tires from that era will have a max of 35 psi. They recommend 30-33 for best mix of comfort and handling. Your tires have a max of 44 psi, so that's better. That means you can definitely fill them up to 44, as the tires are designed to handle that pressure. 44 psi will give you better handling and life than filling them up to a lesser pressure like 35 psi. Only the ride will not be as soft and comfortable as with 35 psi or less. The only thing is that when you have your tires up to their maximum pressure, you need to monitor them as outside temperature changes. If you're filling them up in the spring, and it's going to get hotter out, you need to let some air out to maintain 44 psi as it warms up throughout the year. To maintain max pressure during cooling down months, you need to periodically add air.

[volkerc]

Originally Posted by kaspr

It is important to note that the pressure ratings you see are "max cold tire pressure". So they've accounted for the fact that when you drive, the tires will warm up and pressure will increase. GM's factory tires from that era will have a max of 35 psi. They recommend 30-33 for best mix of comfort and handling. Your tires have a max of 44 psi, so that's better. That means you can definitely fill them up to 44, as the tires are designed to handle that pressure. 44 psi will give you better handling and life than filling them up to a lesser pressure like 35 psi. Only the ride will not be as soft and comfortable as with 35 psi or less. The only thing is that when you have your tires up to their maximum pressure, you need to monitor them as outside temperature changes. If you're filling them up in the spring, and it's going to get hotter out, you need to let some air out to maintain 44 psi as it warms up throughout the year. To maintain max pressure during cooling down months, you need to periodically add air.

wrong and dangerous

[auto trainy]

Originally Posted by volkerc

wrong and dangerous

There must be some tire mfrs out there and I myself would like to know if they recommend me bringing my tire pressure that high and being liable if one blew out.I dont know if this person ever had a blow out at 65 mph,I have and its something you never forget especialy with your family in the car.

[Flatrater]

The tire maker states "Do not exceed 44 psi", that is the most air you can have in the tire but the tire manufacture doesn't list a minimum tire pressure. So if you have 2 psi in your tire it is below the max pressure.


Use the pressure called out by GM which lists the correct pressure for the car, that is why it states "inflate to" instead of "Do not exceed"

[kaspr]

Lower profile tires have the higher max pressures. They're built for more pressure. My 225/55R17's have a max of 44 psi. They recommend a MINIMUM of 35 psi. So to fill it to 30 psi like the original higher-profile 215/70R15 would not apply to my lower-profile tire. Also tires that have a heavier-duty construction you'll find have a higher max pressure rating. You'll find that the really heavy-duty high-speed rated low-profile tires go up to like 51 psi max pressure. All I'm saying here is that different tires are built differently to handle different pressures. I don't see why that is dangerous. To me it is common sense, and I don't know why tire manufacturers would put the higher pressure ratings on their sidewalls if it were dangerous and therefore making them liable.