Question about Tire Pressure (Michelin PS4S 20'')

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Oct 3, 2018 | 10:30 PM

Jinggyjin

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Joined: May 2017

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C63S

Question about Tire Pressure (Michelin PS4S 20'')

Recently got a set of Zito zf01 for my sedan, and I'm currently running 255/30/20 in the front and 275/30/20 in the back. The current tire pressures are about 34 psi all around when cold (35 - 36 psi after 1 hour of highway drive). Do I need to put more air in?
When I'm on stock 19'' rims, I was running 39 - 40 psi all around when cold. Not sure if I need more air for 20''

Thanks for your input!

Oct 3, 2018 | 11:27 PM

RDO247

Super Member

Joined: Mar 2016

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C63S

Quote:

Originally Posted by Jinggyjin

Can you put some pictures up?

Oct 3, 2018 | 11:39 PM

C3504matic

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Joined: Oct 2013

Posts: 418

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From: Edmonton AB

2015 C63S ,DME Tune, KW Has ,Kmac Bushings,BC Forged wheels,Gt Rotors,Porterfield R4S,Modal Intake

I was told to run less with my 285/30/20's , I'm running 36 cold

Oct 4, 2018 | 12:25 AM

RDOCA

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Joined: Jul 2015

Posts: 1,216

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From: SoCal

2016 C63S Sedan

Quote:

Originally Posted by Jinggyjin

39/40 all around on stock tires is not correct.
Look at the label on the back of the gas door.
It is not rocket science guys.
Up to 155 MPH is 38 front and 33 rear.
When you get ready to put on new tires look closely at wear on old and see if you had the right pressure by seeing if wear is even across the tread.
Too much air it wears more in center and not enough more wear on both edges.
Bad balance or alignment will give other wear patterns.
This car has a lot of camber and you might see extreme wear on the very inside edge of both fronts.It is hard to catch unless you check on A lift as it is almost on sidewall.
What ever you do or if you change sizes they are not the same front to rear.

Last edited by RDOCA; Oct 4, 2018 at 12:33 AM.