Yeah, but with VDC on, are you noticing the slip light flashing, hearing/feeling the ABS go off, or feeling the car not keeping its speed during a turn? I thpught a 0.6" difference in tire diameter was acceptable. I know others have run a similar difference. How about slightly deflating the front (since the diameter is larger) and see if that equalizes front to back?

Reducing air pressure in the front tires reduces grip. It causes the tire to roll more in a corner.

i think a camber kit for the front with 2-2.5 degrees of negative camber would help a little bit, but you can also run a 255/285 combo to try and see if the rear doesnt push as hard.

maybe the VDC thing is just my imagination then...

what air pressures should I be running?

my setup:

Hankook V12's

9x9 255/35
9x11 295/30

front = -1.3/-1.4 camber, .04 toe
rear = -1.6/-1.6 camber, .10/.08 toe

Not sure what the factory alignment specs are, but you have twice as much total toe in the rear than the front. I'll take a look at the settings later.

As far as tire pressures, take the factory spec and try +3 in the front and -3 in the back.

changed my tire pressures to 36F and 32R, what a big difference! no more bobbing in the corners. feels like it did when stock now.

ahhhh... I think what you were describing then was turn in not understeer... higher front tire pressure is going to feel more "crisp" when you turn in, but not necessarily give you a greater lateral G before break-away nor tighten up slip angle

glad it's working out

I looked around and was never able to find the factory toe specs. What I was going to suggest is having the car aligned so that the front toe is towards the maximum end of the spec and the rear toe is towards the minimum end of the spec.

By the way, the factory tire inflation spec is 35 psi front and rear. Glad to hear the tire pressure changes helped.

Just in case you're still looking at this, I finally found the factory alignment specs.

Front:

Camber - -1.41 to 0.08 degrees (-0.67 nominal)
Caster - 4.42 to 5.91 degrees (5.17 nominal)
Total Toe - 0.04 to 0.11 inches (0.08 nominal)

Rear:

Camber - -2.16 to -1.17 degrees (-1.67 nominal)
Total Toe - 0.08 to 0.21 inches (0.15 nominal)

They list this spec as total toe in, but above on the rear you list split measurements for toe. So my interpretation is that you have 0.08 inches total toe in the front and 0.18 inches in the rear? If that's correct, since you have the minimum camber spec in the front and close to the nominal spec in the rear, I'd try decreasing rear toe to the nominal spec or slightly lower and see how things are.

That's in degrees, not inches. :tup:

No, that's inches (if you're talking about toe). They did also list the spec in degrees and millimeters..