Tom Pultz

I just had my alignment done yesterday by a local Motorsports shop in the Seattle area that is supposed to be the "guru" on suspension setups... but I find myself questioning how they set my car up with the new 18" wheel and tire combination (225/40 and 265/35-18). As best as I can recall this is how it was set:

Front camber: -1.9 deg
Front caster: +3.2 deg
Front toe: ~0

Rear camber: -1.9 deg
Rear toe: don't recall, but it was just a bit

I think this is going to be too aggressive for a 95% street car, but when I questioned them on it I was told that negative camber on the 944 does not cause excessive tire wear. They said the toe setting determines tire wear.

Maybe... but I had normal toe with another set of tires and I wore the inside edge of the left front after the camber setting changed to -1.7 deg. Resetting the front to -1.2 deg and the rear to -1.7 produced very even tire wear on my last set of 17" tires.

Comments?

K27

I am running -1.5 front with a touch extra toe-in from stock and it drives great on the street, but a little more wear on the inside.
I think 1.9 should be fine if they compensated with toe-in.

Danno

That should be fine. I'm using the following:

FRONT
------
camber: -2.5 degrees
caster: 3.5 degrees
toe-in: 1/8" total

REAR
-------
camber: -2.0 degrees
toe-in: 1/32" total

Camber doesn't does cause as much inside or outside edge wear compared to toe settings because once the tread is flat on the ground, the sidewalls pushing down on them is flexible. However, any toe settings that cause the tire to deviate from the direction of travel causes a scrubbing of the tire sideways, thus wearing out the inside or outside.

Been running on a set of tires for 20k-miles with those alignment settings above without uneven wear. What you might want to do is add some toe-in for street use, then dial in some toe-out for autocrossing.

PorscheG96

I completely agree about the statement regarding toe settings. My previous alignment had too much toe-out and I wore through the front tires in 5k miles...so I flipped them over and got another 4k out of them. At that point I inflated to ~45 PSI and wore down the centers, then they were toast.

Tom Pultz

[quote]Originally posted by Danno:
<strong>What you might want to do is add some toe-in for street use</strong><hr></blockquote>I'm not sure they got enough toe-in. I'll have to look at the sheet again but it's very, very close to 0.

At slow speeds like 30 mph or so, the steering wheel will oscillate back and forth just a bit if you let go of it. It can not be felt while holding the wheel.

Unfortunately, I have not driven the car except back home from the shop and then down to yank the dang clutch out again, so I don't even know how it handles on the highway. They may have to add in just a bit of toe-in for stability. We shall see.

Riff

Tom-

I am running just about the exact same specs as your car (frt -1.8deg, 2.6deg, 0 rr -1.9deg, .06) and have no irregular wear on my street tires after about 6K+ miles.

Not sure why your previous set wore differently. you say you changed the camber to -1.7deg, experienced excessive wear, then changed back to -1.2deg? With the tie rod mounting point in front of wheel center, a change to more neg. camber will increase toe out, if toe is not reset. Excess toe out and neg camber is probably what did in your tires.

The zero toe does make the car feel like it wanders a little on center as it lacks the self centering of toe-in.

Cheers,