New car tire pressures high?

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Tom NJ

Tom NJ

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When I last bought a new car I found the tire pressures well north of 40 psi while the door placard recommended 32 psi. I was told at the time that the manufacturers typically set new car tire pressures high to accommodate shipping conditions (?).

So now I just bought a new Nissan Altima 2.5 SL and sure enough the tire pressures are high again, all four at 45 psi vs a placard pressure of 33 psi. I reset them to 36 psi.

Do all car manufacturers routinely set tire pressures that much higher than the placard pressure? If so, why? If related to shipping, then shouldn't the dealer reset the pressures to the placard pressure?
 
Originally Posted by Tom NJ
Do all car manufacturers routinely set tire pressures that much higher than the placard pressure? If so, why? If related to shipping, then shouldn't the dealer reset the pressures to the placard pressure?

Yup... they set pressure high to minimize flat spotting and such.

I've also read a tire needs to be inflated to over 40 PSI to properly seat on the rim during mounting, so that could be another reason. Not sure if factory uses the same mounting techniques as regular tire shops.

And yes, the dealer is supposed to reduce that pressure to the correct value as part of routine new car prep. Some dealers are lazy.
 
Originally Posted by Quattro Pete
... And yes, the dealer is supposed to reduce that pressure to the correct value as part of routine new car prep. Some dealers are lazy.

It is called a PDI , pre delivery inspection. There is a checklist. The car is supposed to have the oil checked, shipping tie downs or spring cushions removed, washer fluid added, some gas put in, re-programmed to exit transport mode if equipped, wheel centre caps or hub caps installed, wheels torqued and tire pressure adjusted ...

Some TECHs are lazy ...
 
They ship these things on ships and trains. High pressure is good for shipping. Also good for when its sitting on a lot for 6 months to a year.
 
Hmmmm, I didn't know this. When I got my CR-V (the last new car I've purchased), the pressures were all at 45PSI. It calls for 29. I run it at 33.
Thanks for the info.
 
I know that tires are inflated higher for transport on ships. I didn't know the same was done for rail as well.

It seems to be a common issue though. Always recheck your tire pressures after you get your vehicle. Mine were supposed to be at 32 but the pressures varied all over from 36 down to 27psi. I reset all of them to 34psi.
 
Originally Posted by Quattro Pete


I've also read a tire needs to be inflated to over 40 PSI to properly seat on the rim during mounting, so that could be another reason. Not sure if factory uses the same mounting techniques as regular tire shops.


I have never had it take more that 20 PSI to seat a tire bead. In fact if it got to 40 without seating something is wrong.
 
Originally Posted by Tom NJ
When I last bought a new car I found the tire pressures well north of 40 psi while the door placard recommended 32 psi. I was told at the time that the manufacturers typically set new car tire pressures high to accommodate shipping conditions (?).

So now I just bought a new Nissan Altima 2.5 SL and sure enough the tire pressures are high again, all four at 45 psi vs a placard pressure of 33 psi. I reset them to 36 psi.

Do all car manufacturers routinely set tire pressures that much higher than the placard pressure? If so, why? If related to shipping, then shouldn't the dealer reset the pressures to the placard pressure?


They set them "high" the same reasons most folks do

1. Wear better
2. Less liability and likelihood of error
3. Less likely to develop flat spots
4. Seals bead better

While there are ZERO safety issues associated too high a pressure (even up into true over inflation)

There is imminent issues with under inflation like spontaneous blowouts and bead separations

As a car manufacturer you need the car to always arrive with a minimum pressure or risk having to replace a tire on a virgin car.

Putting in slightly higher pressures 45-55psi has zero negatives but is cheap insurance from tire damage due to a low leak or temperature change.

As for why the dealer doesn't adjust down its laziness
After all who wants to adjust tire pressures weekly on hundreds of cars due to weather fluctuations?


In my case I've always experienced the opposite problem where the dealer drops pressures to 32psi every time they touch my car that calls for 38psi
 
Last edited:
My car's placard calls for very high pressures anyway (39 PSI front, 36PSI rear), and I run them at 44 front, 41 rear.

I do not remember what they were at right from the dealer.
 
Originally Posted by Rmay635703


While there are ZERO safety issues associated too high a pressure (even up into true over inflation)


Putting in slightly higher pressures 45-55psi has zero negatives but is cheap insurance from tire damage due to a low leak or temperature change.



So no adverse handling issues with the decreased contact patch (at higher psi ground contact) between tires at 30 psi vs tires at 40 psi (for example)? Not sure I agree with that but do agree that higher than placard is safer than lower. Most P rated tires have max inflation around 41-42 psi.
 
I bought a new Hyundai once and first time on the highway it felt like I was driving on roller skates. Checked the tire pressure when I got home, was I think 52 or 53psi. Door placard said 32. Couldn't believe it.
 
Originally Posted by AZjeff

So no adverse handling issues with the decreased contact patch (at higher psi ground contact) between tires at 30 psi vs tires at 40 psi (for example)? Not sure I agree with that but do agree that higher than placard is safer than lower. Most P rated tires have max inflation around 41-42 psi.


Handling, no, actually better against hydroplaning steering is much more responsive
Ride quality definitely poorer

All my car tires are 50 or 51 psi rated
door placards 35-40psi

Truck has 70psi rated tires


All the manufacturer worries about is under inflation since that will kill a new tire.
 
Originally Posted by AZjeff
Originally Posted by Rmay635703


While there are ZERO safety issues associated too high a pressure (even up into true over inflation)


Putting in slightly higher pressures 45-55psi has zero negatives but is cheap insurance from tire damage due to a low leak or temperature change.



So no adverse handling issues with the decreased contact patch (at higher psi ground contact) between tires at 30 psi vs tires at 40 psi (for example)? Not sure I agree with that but do agree that higher than placard is safer than lower. Most P rated tires have max inflation around 41-42 psi.


Too high of tire pressure will also wear the tire unevenly, wearing out the center of the tire at a faster rate than the edges.
 
Originally Posted by Rmay635703
Originally Posted by AZjeff

So no adverse handling issues with the decreased contact patch (at higher psi ground contact) between tires at 30 psi vs tires at 40 psi (for example)? Not sure I agree with that but do agree that higher than placard is safer than lower. Most P rated tires have max inflation around 41-42 psi.


Handling, no, actually better against hydroplaning steering is much more responsive
Ride quality definitely poorer

All my car tires are 50 or 51 psi rated
door placards 35-40psi

Truck has 70psi rated tires


All the manufacturer worries about is under inflation since that will kill a new tire.


My experience has demonstrated significantly poorer traction with higher inflation pressures, even ones that were within the acceptable pressure envelope for the vehicle. Traction is the reason you run low pressures at the drag strip. Over-inflation will reduce the contact patch and while it may make the steering feel "more responsive" (twitchy), overall lateral traction/hold can be reduced.
 
My new ‘17 Mazda6 was delivered with 55psi. Placard was in the 30's. The PDI form was still in the glove box without a mark on it.

Every used car I bought has had the spare delivered with less than 40psi(60 required). I even gave the dealers low CSI scores and never heard anything.

It goes to show that nobody cares whether you leave the lot with the car properly prepped.
 
Originally Posted by DerbyDave
Originally Posted by AZjeff
Originally Posted by Rmay635703


While there are ZERO safety issues associated too high a pressure (even up into true over inflation)


Putting in slightly higher pressures 45-55psi has zero negatives but is cheap insurance from tire damage due to a low leak or temperature change.



So no adverse handling issues with the decreased contact patch (at higher psi ground contact) between tires at 30 psi vs tires at 40 psi (for example)? Not sure I agree with that but do agree that higher than placard is safer than lower. Most P rated tires have max inflation around 41-42 psi.


Too high of tire pressure will also wear the tire unevenly, wearing out the center of the tire at a faster rate than the edges.


But not sitting in a ship then a lot up to a year, deflated tires are a huge source of damage during transit, loss prevention nothing more
 
Originally Posted by Garak
I shouldn't say this too loud lest I be heard, but I'm surprised they don't jack the pressures up on the placard for CAFE concerns.


I think the ZERO grip, low rolling resistance OE tires have that covered ...
 
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