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psi for wider tires?

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#1
I've been running 315/35R20 Contis on 20x11s. I've had the PSI set to 29-30 for most of the tire life (which has been short).
They're worn and upon inspection they are showing heavier wear down the center--meaning they've been over inflated...
Thus my question... what PSI do people run with the wider rears to get even wear and an even contact patch? How low do you go? :)
 

The Englishman

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#2
I too,have always wondered the answer to this,I very rarely have a car with original wheels/ tyre sizes so I go factory pressures.
 

DGatzby

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#3
I have not pulled out the old 315/35 on an 11" picture for a while. Does it resemble this? IMG_0585.JPG
 

BULL

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I haven't tried this myself, so I don't know how legitimate it is, but I've heard it said that if you take chalk and draw lines from one sidewall to the other, and then drive on it down the street, observing how the chalk is removed differently between the sidewalls and the center, you can adjust the pressure in this way until the chalk is "evenly" removed.

Sounds sketchy...
 

Loucifer

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#5
28psi cold is working good on my 305 555r's. I am at 4/32nds, 3 points across.
 

landoawd

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#6
I haven't tried this myself, so I don't know how legitimate it is, but I've heard it said that if you take chalk and draw lines from one sidewall to the other, and then drive on it down the street, observing how the chalk is removed differently between the sidewalls and the center, you can adjust the pressure in this way until the chalk is "evenly" removed.
This is absolutely a way to do it. It's my preferred method on 4x4s.

You can also do corner-weighting and load calcs. Easy math.
 

BULL

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#7
This is absolutely a way to do it. It's my preferred method on 4x4s.

You can also do corner-weighting and load calcs. Easy math.

For the second method you reference, do you start with the factory weight/corner and then create a ratio based on increase/decrease of width?
 

landoawd

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#8
All tires have a load rating. Technically, you could take gross weight an quarter it, but you lose accounting for distribution. Then, find the PSI for the load and set it.
 

SunnyS

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#9
I like the burn out method .Even patch means right tire pressure
 

YMMV

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#10
This is absolutely a way to do it. It's my preferred method on 4x4s.
Agreed. I did the same when running 33s & 35s back in the day.
 

PaVaSteeler

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#11
Pardon my ignorance, but what made you change the psi from the 32 lb specified on the door plate?
 

landoawd

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#12
Load rating, actual width, etc all play a part. 32 is usually fine.
 

Jimmy N.

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#13
I start with going by what a load chart suggests and go from there. You need to know your actual axle weight, though. The chalk method usually works, too.

Once changing rim width and/or tire size, the door sticker means nothing.
 
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#14
I've been running 315/35R20 Contis on 20x11s. I've had the PSI set to 29-30 for most of the tire life (which has been short).
They're worn and upon inspection they are showing heavier wear down the center--meaning they've been over inflated...
Thus my question... what PSI do people run with the wider rears to get even wear and an even contact patch? How low do you go? :)
Hi I’m sure James has what you are requesting for you can message him on donald56787@gmail.com


Sent from my iPhone using Tapatalk
 

DGatzby

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#15
For the street damn near as low as you can without tripping the low air warning. 29-30 psi cold. I do. I believe it trips at 28, but check me on that.
 

Stormtrooper1320

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#16
I haven't tried this myself, so I don't know how legitimate it is, but I've heard it said that if you take chalk and draw lines from one sidewall to the other, and then drive on it down the street, observing how the chalk is removed differently between the sidewalls and the center, you can adjust the pressure in this way until the chalk is "evenly" removed.

Sounds sketchy...
Sometimes the simple way works best. I like it. And just so you know.....I'm gonna try it when I put my drag radials back on when the weather warms up. And yes.....I'll make sure you get full credit :)
 

why2kmax

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#17
indy 500s in 305/35/20 on 20x11 rims 31-32psi and I have even wear across the tire all the way down to 4/32nds
 

hellno

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#18
Wow I run my firestone Indy 500 at 34 and no unusual wear
 


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