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What's a normal tire pressure?

G

GigaCluster

Golden Member
I have a Mazda MX-6 (1993) -- a rather small car -- with four quite new tires. The left front recently started making a rapidly flapping noise when the car was going faster than about 30 MPH, so I assumed that the tire may be underinflated. I measured it and the pressure was about 30 psi. I looked on the tire and it says that the pressure limit is 55 psi. So, I filled up all four tires to slightly less than 50 psi. The flapping noise is no longer present.

I then ask my dad what the proper fill is and he says that it is about 32 psi. However, based on experience, I don't trust anything he says of this nature. So, can anyone tell me what my optimal tire pressure should be? Is ~50 psi too much?
 
YES it's WAY too much

don't look at the tire at all, look at your owner's manual to figure out the correct PSI
 
i think tires are supposed to be more inflated at high speeds meanihg over 100mph. on a 97 tl the tire pressure for the front is 32 and i think 35 for the rear
 
Originally posted by: Cooljt1
i think tires are supposed to be more inflated at high speeds meanihg over 100mph. on a 97 tl the tire pressure for the front is 32 and i think 35 for the rear
Click to expand...

Those are pretty much the limits of inflation...

GigaCluster...I'd get some air out of that thing RIGHT now..that is dangerous as hell. Also, the more inflated the tire is the less surface area will be of contact....


Good luck in the rain...
rolleye.gif
 
Deflate the tire NOW! Normal pressures run anywhere from 30-35 psi. As said above, check the driver's door jam for proper inflation numbers.
 
Thanks, everyone, for the info. I deflated all tires to about 35 psi and hope that they weren't too damaged by this incident. They were inflated to slightly OVER 50 psi for several days, according to my measuring tool. (Does that have a name, BTW?) Well, let this be a lesson to me.

Now, I looked on the door jamb and it does not say anything about tire pressure. What it does have is three columns of weights:
GVWR: 3460 lb (1569 kg)
GAWR FRT: 1980 lb (896 kg)
GAWR RR: 1480 lb (674 kg)
Can I determine the optimal tire inflation based on those masses?
 
I then ask my dad what the proper fill is and he says that it is about 32 psi. However, based on experience, I don't trust anything he says of this nature.
Click to expand...

Dad was right. 🙂
 
There should be a sticker either on the edge of the door or on the door jamb. It will spell out the tire pressures for different size tires and loading conditions. Else see your owner's manual.

The brand of the tire has nothing to do with inflation pressure.

The pressure on the side of the tire is the MAXIMUM inflation pressure.

There's no such thing as "normal" pressure. It depends on the size of the tire and the vehicle. The rear tires on my BMW 528 take 41 psi, while the fronts take only 33 psi.

But I would guess your MX-6 would likely be in the ~30 psi range, since you probably don't have low profile tires.

The measuring tool is called a tire pressure gauge.
 
I also own a 1993 Mazda MX-6. My owner's manual says:

Front: 32 PSI
Rear: 26 PSI

That rear spec sounds low to me. It may also depend on whether you're running the make and exact size of your tires. Check with a tire shop for more info. The shop where I bought my last set inflated them to 32 PSI all around.
 
You can inflate the tires to whatever it says on the sidewall, but it's not as comfortable as it would be if you were to fill to the car spec.

BTW, to whoever says that inflating that high decreases the amount of tread that contacts asphalt, you don't know that for sure. Maybe the tread is still flat. And anyway, about that rain comment, if there's LESS tread area, the tire works BETTER in rain. Pressure = force/area, therefore less hydroplaning.
 
Be warned the numbers that are on the door and car glove box etc... are when the tire is COLD. So if you set your tires to what the car sayd, you may be off if you just drove or drove it to the gas station etc...

A good year round tire pressure that seems to wear the tires pretty even is 36front and 32 rear.
 
Originally posted by: Howard
You can inflate the tires to whatever it says on the sidewall, but it's not as comfortable as it would be if you were to fill to the car spec.

BTW, to whoever says that inflating that high decreases the amount of tread that contacts asphalt, you don't know that for sure. Maybe the tread is still flat. And anyway, about that rain comment, if there's LESS tread area, the tire works BETTER in rain. Pressure = force/area, therefore less hydroplaning.
Click to expand...


Yes, you do know that. The faster you are traveling, the more the center of the tire flares out due to centrifugal force.. and the less contact you have with the road.
 
i run 120 front and 95 back. I like to have a minimal footprint with the road, and that's why even in the maxima I can get 50 mpg city. Also on the sentra it will spin into 5th gear from lack of traction.
 
Originally posted by: Howard
You can inflate the tires to whatever it says on the sidewall, but it's not as comfortable as it would be if you were to fill to the car spec.

BTW, to whoever says that inflating that high decreases the amount of tread that contacts asphalt, you don't know that for sure. Maybe the tread is still flat. And anyway, about that rain comment, if there's LESS tread area, the tire works BETTER in rain. Pressure = force/area, therefore less hydroplaning.
Click to expand...

Hydroplaning is one thing. Normal traction is another. If you aren't hydroplaning, bigger contact patch is better in the rain. How often do you hydrplane?
 
Originally posted by: Goosemaster
Originally posted by: Cooljt1
i think tires are supposed to be more inflated at high speeds meanihg over 100mph. on a 97 tl the tire pressure for the front is 32 and i think 35 for the rear
Click to expand...
Good luck in the rain...
rolleye.gif
Click to expand...
WinkOsmosis ^
 
Originally posted by: Eli
Originally posted by: Howard
You can inflate the tires to whatever it says on the sidewall, but it's not as comfortable as it would be if you were to fill to the car spec.

BTW, to whoever says that inflating that high decreases the amount of tread that contacts asphalt, you don't know that for sure. Maybe the tread is still flat. And anyway, about that rain comment, if there's LESS tread area, the tire works BETTER in rain. Pressure = force/area, therefore less hydroplaning.
Click to expand...


Yes, you do know that. The faster you are traveling, the more the center of the tire flares out due to centrifugal force.. and the less contact you have with the road.
Click to expand...
I'll not be anal and state that there's no such thing as centrifugal force. 🙂 Perhaps the center does flare out, when mounting in free air, but I don't believe that the tendency to move outward overrides >600lbs.
 
Howard's dead on. Whoever said that underinflated tires in the rain was a good idea was an idiot.

I say "was" because he probably lost control on a rainy night and got washed off a guardrail with a firehose.

- M4H
 
The maximum pressure on the tire is the pressure for the tire's maximum load rating. Use the pressures listed on your car's doorjamb and not the pressures from the tires.

ZV
 
Let me describe my little tire event. I have expensive(around $200 each) tires and on the sidewall it says that max pressure is 35. I thought that sounded good, so I inflated my tires to 35. I went on a roadtrip and about a month later my tire blew. When I took it off the tread on the inner and outer side of the tire was all the way down to the metal, and on the other side the front tire was the same way. About 30 psi is what you normally should be running. When they say max, they mean MAX!! I learned this the hard way...........:|
 
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