# How does uneven tire pressure affect a car's ride?



## Gogie (Oct 11, 2013)

First post but a long time lurker (and a BMW driver for a little over 3 years). Picked up a new 2013 535i xDrive (M sport) a few weeks ago after leasing a 335i xDrive for 3 years. Quick question - if the tires on one side of the vehicle are inflated with 2 PSI pressure more than the other side would this have a noticeable effect on the ride?


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## lib (Dec 24, 2001)

Gogie said:


> First post but a long time lurker (and a BMW driver for a little over 3 years). Picked up a new 2013 535i xDrive (M sport) a few weeks ago after leasing a 335i xDrive for 3 years. Quick question - if the tires on one side of the vehicle are inflated with 2 PSI pressure more than the other side would this have a noticeable effect on the ride?


2psi? At most speeds no... I expect passenger and cargo weight distribution affect the pressure a bit too and it isn't noticeable.

I have a leaky right rear that loses pressure in the cold.... It'll drop 5+ psi and I won't feel any pull

Sent from BimmerApp mobile app


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## SippinSomethin (Oct 16, 2013)

lib said:


> 2psi? At most speeds no... I expect passenger and cargo weight distribution affect the pressure a bit too and it isn't noticeable.
> 
> I have a leaky right rear that loses pressure in the cold.... It'll drop 5+ psi and I won't feel any pull
> 
> Sent from BimmerApp mobile app


^This. I had a right front tire that was losing pressure and the car wouldn't start driving funny until it lost 8+ psi. Although i'd say keep em' as close as possible, especially if you like the track. :thumbup:


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## jadatis (Sep 15, 2009)

In all documentation you will find that both wheels on an axle have to have the same pressure.
But for motorhomes for instance there is often a big diffence in load between the tires on an axle because of things placed out of the middle .
And because the pressure for higher load needs to be higher, you would expect a different pressure R/L.
But also there same pressure is adviced.
Arguments in pro of that could be to my conclusion next.

A higher pressure makes the sidewall stiffer, and so same stifness with same pressure, makes the sideward forces on the tires to be equally divided, because for sideward forces the weight on the axle is only important and not the weight/difference.

But same pressure gives for unequall loads R/L more deflection of the tire at the higher load.
wich tordates the frame. These torsion-forces of the frame compensate a bit the weightdifference between R/L, so what you should weigh if you do a 4 point weighing.
This is also positive for the riding quality I think.

If you then by some way should level the car, so wheelsheelds( correct me if I use a wrong word) on same hights R/L, the torsion forces are brougt back to zero and the real weightdiffences pup up.

Yust some arguments to considder, do with it what you want.


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## drrpm (Feb 9, 2010)

A difference of 2 PSI will make no noticeable difference under every day conditions. You might notice on a track if a pro driver was making runs and you were timing it.
How much difference in performance is there between a having a driver alone and a driver with 1 passenger? Probably more than 1 tire having 2 PSI more than the other.


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## Paul335i (Aug 18, 2012)

A different tire pressure between L + R can shorten the life of a LSD.


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## captainaudio (Jul 17, 2007)

Paul335i said:


> A different tire pressure between L + R can shorten the life of a LSD.


It would very likely require more than a 2PSI difference.

CA


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