what tire pressure to go by??

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Should I go by the recommended tire pressure on my car label??? or do I go by the tire manufacturer recommendations??
And what if I put in 32 or 34 lbs instead of say 30 as called for on the car???
 
You go by the PSI on the car label, and can adjust a few PSI up from there.

The tire manufacturer only lists the MAX allowable PSI, but they have no idea what car you're going to mount their tires on.
 
There is a direct relationship between "slip angle" which affects handling, tire wear, and ride quality. For a particular vehicle, there is usually a sweet spot, but that can vary depending on the actual tire on the car. The car companies have a tire pressure in mind which is a good compromise based on what they are supplying as OEM , but if you go up a rim size and width and fit a "performance" tire with a stiff sidewall and additional belts, it may be well off. The companies can't control what you replace OEM with. For example, overinflation usually affects a wider tire sooner than a narrow one. Radials don't telegraph underinflation to the driver as quickly.
In the racing world, tire pressure is set by using a "tire pryometer" which measures temps across the tread. The techs shoot for even heating. Hot spots point to inflation problems and/or alignment issues. We can't do that with a daily driver, so using an accurate gauge and getting a feel for adjustments is the best we can do. Don't just assume that more air is better.
 
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If you are using the same tire size as listed on the vehicle tire placard, then the pressure listed there is appropriate. If you are using a different size, then the pressure has to be recalculated. The calculation isn't difficult, but it involves the use of tire load tables which are not published on the internet. But I have a copy and am willing to it.

As others have indicated, what is written on the sidewall of the tire is NOT a recommendation.

And lastly, a few more psi is not a big thing. But be aware that ride quality suffers as pressure goes up.
 
I usually start at oem +2psi to +4 psi and adjust from there.

in my case its 32/30 which felt way to soft.

35/33.5 is pretty good.. and if I'm towing long distance I bump the back up to about 36-37

I had tried 36psi all around but it felt abit harsh.
 
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No arguments with the repiles; but like most people, I don't check the pressure as often as I should; so I always go above the listing on the door jambs. Wear from underinflation is far more common than the opposite.
 
Originally Posted By: Rand
I usually start at oem +2psi to +4 psi and adjust from there.

in my case its 32/30 which felt way to soft.

35/33.5 is pretty good.. and if I'm towing long distance I bump the back up to about 36-37

I had tried 36psi all around but it felt abit harsh.


That is what I've always done too.
 
Originally Posted By: CapriRacer
If you are using the same tire size as listed on the vehicle tire placard, then the pressure listed there is appropriate. If you are using a different size, then the pressure has to be recalculated. The calculation isn't difficult, but it involves the use of tire load tables which are not published on the internet. But I have a copy and am willing to it.

As others have indicated, what is written on the sidewall of the tire is NOT a recommendation.

And lastly, a few more psi is not a big thing. But be aware that ride quality suffers as pressure goes up.


Best to keep same tire size and the PSI on the manual and/or door sill. Straying from that will cause problems from a balanced perspective (ride, handling, tire life, load capacity).
 
For some reason the rear PSI for rear tires on a empty pickup truck is too high. For my trucks they call for 35 PSI rear but I'll lower them down to 26 PSI. Before carrying a heavy load I'll air them back to 35 PSI or higher.
 
About a year ago I put on four new tire (General Altamax HP's).

The vehicle sticker (03'Ford Focus) states 32 PSI. I run it up about 10% to 35....which seem to me to be the sweet spot for my vehicle.

My reasoning is to get a little better mileage. It seems not to effect wear. The tires are all wearing evenly.
 
Originally Posted By: wirelessF
For some reason the rear PSI for rear tires on a empty pickup truck is too high. For my trucks they call for 35 PSI rear but I'll lower them down to 26 PSI. Before carrying a heavy load I'll air them back to 35 PSI or higher.


Most owners won't do that, and that's the reason why pickup truck inflation settings are the way they are. They're often set to be at or near the maximum load rating for the tire installed (which would be 35 psi for a P-metric tire). This is necessary to carry the payload for which the engineers have designed the truck. Most owners won't think to raise the pressure for carrying loads, and they'd overload the tires if they put in the maximum payload while the tires are underinflated. So the pressure is set where it is accordingly.
 
Originally Posted By: lucerne06
Should I go by the recommended tire pressure on my car label??? or do I go by the tire manufacturer recommendations??
And what if I put in 32 or 34 lbs instead of say 30 as called for on the car???


GO BY THE STICKER ON THE CAR. The tires get used in many applications, and the maximum PSI/Load rating shown on the tire is just that... its the max the TIRE can handle, but may not be appropriate for your car.

Now to be honest- 32 vs 30 lbs isn't going to make a car unsafe to drive. But a similar change in a top-heavy SUV or truck could be dangerous or cause abnormal wear, and a ~10 PSI increase in a car could potentially be dangerous or cause abnormal tire wear.
 
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