nostim

Now here is a guy with a theory. This is exactly what I was thinking. Good job.

hayespa

I adjusted the pressure to 30 front, 32 rear and noticed that the decel noise decreased. Still there but less. Not sure I want to leave the front at 30 as I felt the lower pressure immediately. Not as tight.

boomn29

iTrader: (47)

If you put extra pressure in the rear, your tires are going to wear out quicker, possibly through the middle. Maybe not much with 2 lbs, but you get the idea.

I was running 29 in the rear of my Celica (hatchback) where there is no weight in the back, and after about 6k miles, you could see the center of the tire balding. I reduced it to like 24psi and they wore evenly.

Just depends on your weight distribution relative to the vehicle. Our EVO's are more even, but still that engine weighs more on the front then the trunk on the back!

Hanzo

How is 2 lbs more in the back different from the factory (32/29
"3" lbs more in the front)? According to your logic the factory setting will wear unevenly even more since more pressure are in the front tires. They are not equal to begin with. This setting actually has less variant between front to rear. Also keep in mind this car is AWD.

Different tires size has different optimal pressure therefore for the Celica tires might require less pressure than the 235 45 17 that is on the Evo.

BTW the rear of the Celica (hatchback) is probably has the same amount of weight to the rear if not more than the coupe since the rear hatch glass is very very heavy along with parts like hydraulics to hold the hatch. BTW I used to have a Celica hatch as well.

96_LXR

iTrader: (3)

I have been chasing the "decel noise" issue since my car hit about 38k.

After reading this post i gave it a try and the noise (and slight vibration) has improved by at least 90%

I am running 2psi more in the rear and tthe car now only gets a slight buzz when it goes thru about 25 MPH.

I am gonna try changing the rears slightly to see if I can get it any better but just wanted to say thanks for the tip!

My car is my DD and I go over a mountain on the way to work and on the downhill side is where I really noticed the vibration.

Thanks!

waynea

iTrader: (1)

I recommend against this practice. We accidentally swapped the front and rears on my 06 MR after some improvements and during testing we found the rear of the car to be very prone to snap oversteer. Snap oversteer is the condition were one is telling the officer about how everything was fine and then suddenly the car veered straight into the telephone pole. I can only compare my tire pressure induced overstreer to feeling one gets from being on the bump stops as I have often experienced in not so sporty RWD cars, Tbirds, old Caprices, base model Mustangs, etc. Testing was done in a private area away from city streets, telephone poles, etc. Resetting the pressures to the factory offset greatly reduced the oversteer condition.

Under engine braking, i.e. slowing down with the clutch engaged and the throttle closed, larger tires in the rear would keep the driveline loaded. Smaller rears would let the driveline rattle. Do you have a bad u-joint or something loose. Also, can the noise be reduced by not engine braking, simply press on the clutch while braking and let the car coast to a stop. This is probably better for saving the car and gas than engine braking anyway.

Does anyone know if there was a reason that Mitsu designed the car this way, i.e. did they want smaller rear tire to unload the transfer case/driveline and then tuned the suspension for with rears at a lower pressure or did the just find during testing that they got better performance with lower pressure in the rears. As they require the same tire on the front and rear I have to guess that Mitsu had a reason for designing the pressure offset. Just noticed that boomn29 has the best theory, better contact patch with the lower loading of the rear tires.

Besides we bought the Evo because of the way it handles, if one really cares about less noise get a Caddy or at least check out the stereo forum for how to install sound deadening materials.