Hanzo

I recently rotate my tires front to rear and notice the deceleration noise we get is lessen to “almost” gone. I had the factory tire pressure spec before I rotated them so it was 32 pounds in the front and 29 pounds in the rear. Now after the rotation I have 29 in the front and 32 in the rear. I might increase the front 1 pound more to make it 30/32.

The old WRX had the same problem with deceleration noise like the evos and that was one of the way (increase tire pressure in the rear by 2 pounds compare to the front) suggested by Subaru of America to reduce the noise.

WestSideBilly

iTrader: (1)

This has "accident waiting to happen" written all over it.

evo 8 ya

iTrader: (31)

that might lessen the tire noise but not the decel noise

Hanzo

2 pounds difference only effects handling (increase oversteer) I am not saying go out and do it, if you can't handle the car then don't do such change.

Tire noise is not an issue, I am talking about the "decel noise".

Secret Chimp

iTrader: (2)

right....as noted above. Messing with tire pressures only serves to moderate the tire slapping road noises. It does nothing to change the deceleration noises which mostly come from the tranny and transfer case.



SC~

mprtklr

iTrader: (7)

i would be curious to see how affecting tire pressure is going to help a noise that is in no way related to tire pressure.???..

"i've learned that the best way to cure brain cancer is to cut off your pinky toe."

prowler

I guess whatever works for him!

wasAudi_nowEvo

Everything that I know sez that lower pressure in front will make it UNDERSTEER, not oversteer. No fun to drive, but probably not dangerous....

Not sure why rotating would affect the noise much.

Slightly OT, but my Yokohama AVS Winter skins were a LOT quieter than the A046's.

sir lurks alot

iTrader: (2)

It makes sense to try it. The different pressures would equate to different diameter wheels front to rear. This may offset some tolerance in the transfer case. Possible, but worth a try either way.

Hanzo

I didn't believe it either when Subaru told me about it to try it on my WRX but it works. And it also works on the Evo. I’ve been around cars long enough to tell the difference between tire noise and decel tranny noise.

Hanzo

Oversteer is cause by lost of traction in the rear wheels which will be true if more pressure is in the rear creates a more rounded contact patch which in terms create less contact spot to the surface compare to the front. Understeer is the vise versa.

Secret Chimp

iTrader: (2)

Low pressure causes a tire to buckle when loaded and will lead to a smaller contact patch also. It's a game to find the point between the overinflated balloning of the contact patch and the underinflation buckling where you get maximum traction. So saying adding psi will decrease and releasing pressure will increase traction is only as good as the reference point from where you are starting.

So how can playing with tire pressures effect the noise eminating from the drivetrain?

SC~

Hanzo

Keep in mind my tire pressure is NOT lowered, they are just swapped around front to rear.

I NEVER said release pressure, I say change the ratio to have 2 more pounds in the back vs the front.

I can't tell you why it works because truly I don't know but it DOES work, if you guys want to try it that’s fine if not that’s cool too, but I just want to share my finding with my peeps that’s all.

Braf

Tire pressure has an impact on effective wheel circumference. The smaller circumference up front induces load on the drive train. As the gears are under load the rattle normally heard is reduced or eliminated.

Hanzo

Interesting...