tire pressure PSI - go by tire or by manufacturer's specs?

[TheNinja]

So my tires say "max 44 PSI". I usually just put in around 38-40. However today I got my oil changed and they said manufacturer recommends 30 so they put 30 PSI in. It seems like my gas mileage is going to suffer and the tires won't wear correctly. Which is correct?

 

[Heisenberg]

Always inflate to the what the vehicle specs say either in the door jam or in the owner's manual. The rating on the tire is the maximum, not what it should be operated at normally. The 30 PSI number is evidently what yours should be inflated to. Overinflating to 40 PSI will cause uneven wear and degrade handling.

 

[mercanucaribe]

The tire max pressure has nothing to do with what you should put in. That's the max that the tires can handle without popping. Different cars have different weights and so need different pressures. You probably will get worse gas mileage, but the wear will be more even. Too high a pressure will put more wear on the center of the tread.

 

[FrustratedUser]

Originally posted by: TheNinja
So my tires say "max 44 PSI". I usually just put in around 38-40. However today I got my oil changed and they said manufacturer recommends 30 so they put 30 PSI in. It seems like my gas mileage is going to suffer and the tires won't wear correctly. Which is correct?

Always follow the vehicle specs.

 

[Kaervak]

I go by what the vehicle MFG suggests. My last set of tires lasted a little over 50,000 miles which is what they were rated at. If you want to get really accurate PSI for your particular car, wait till the tires are completely cool. Then draw a chalk line perpendicular across the treads on each tire. Take note of where the chalk wears and adjust the PSI to keep the wear even across the entire tread. Takes a bit of work, and is a little bit of a PITA, but you *should* have accurate PSI settings for each tire.

 

[TheNinja]

Cool thanks guys. Confirmed what I thought. Once again ATOT comes through. I guess I'll just leave them at 30 then.

 

[GrantMeThePower]

What if the tire max is less than the mfg spec?

 

[FrustratedUser]

Originally posted by: GrantMeThePower
What if the tire max is less than the mfg spec?

The you got the wrong type of tire on your car.

 

[RagingBITCH]

Um, why the hell are you going by the "max" pressure? What logic gave you that idea?

 

[Cattlegod]

RTFM

Read your owners manual for your car. It will say the recommended tire pressure. Use that one period. All of the NVH and vehicle dynamics testing was done using that pressure in the owners manual.

edit: and it is probably 32 or so.

 

[chuckywang]

Originally posted by: TheNinja
So my tires say "max 44 PSI". I usually just put in around 38-40. However today I got my oil changed and they said manufacturer recommends 30 so they put 30 PSI in. It seems like my gas mileage is going to suffer and the tires won't wear correctly. Which is correct?

Max PSI is just that...the maximum PSI your tire can have. It's very different than the recommended PSI, which is what you should use.