I am still not using all the tire width (especially on the rears).

Now, my wheels are 19x10 (56mm) fronts, and 20x11 (79mm) rear,
my tires are Toyo R888 295/30/19 and 315/30/20.
And I have LG Motorsports G7 sway bars.
This is on a 2014 C7 convertible, MN7, Z51, MRC.
I lowered the car on the stock bolts right to the bottom (got about 5/8").

My first alignment was -1.8 and 1/16" toe out on each front,
-1.3 zero toe on each rear.
I had been running the tires at 38 and 33 cold.
I did have some "rub" (not on the track), but on the highway driving to/from events. The rub was on the top fender lips... not wearing away any fiberglass; just taking some rubber from the tires (not enough to worry about).

To get more contact on the rears I changed the alignment
-2.2, 1/8" toe out on each front,
-1.8, 1/16" toe out on each rear (I know... toe out in the rear is NOT recommended).
I also dropped the pressure to 33/27 cold.
Oh, we also removed ALL the washers from all the upper A-Arms.
(Yeah.... 2 washers on each bolt.... 32 washers in all).

This did work, in that the rears are now showing much more tread is being used.

But I was still getting some "rub", and the rears are not showing full use across the face yet.

So we raised it back up to factory height (about 5/8" higher).
That SHOULD fix the "rub".

Now I want to put more camber in... front and rear.
By removing the washers, this SHOULD be attainable.

But in the 2015 manual it says to remove only 1 washer from each bolt.

So.... am I going to encounter any "problems" by removing 2 washers from each bolt? If so, what problems ?

Thanks

 

I can not think why removing both washers would be off limits. I had to remove one washer from each rear in order to get more camber and to get the rear toe set into "0".

Without removing the washers my max rear cambers were only -.6 driver and -.9 passenger sides. But, at those values I was all maxed out on the toe adjustment and ended up with a slight rear toe-out vs. 1/16 toe-in up front. Felt Ok but, in the 90-100MPH corners that rear toe-out was making the hair stand straight up my back... :-).

After removing only one washer from the rear mounting points I got my specced -1.3 rear cambers with a range of adjustment for the rear toe. I settled for 0 rear toe.

I have the FE3 suspension, shocks and sway bars, and am not all that happy with the handling. Tomorrow should be getting the FE4 larger rear swaybar + bushings. Hope that will fix the understeer that I am battling, before I commit to one of the aftermarket set of swaybars. I certainly like the looks of the aFE bars with dual front and triple rear adjustability.

You did not mention what was your usage was for the car. Since it is a vert, I assume either no high speed track usage or very limited ones. Asking because for the street your camber and toe adjustments are rather aggressive. How do you check for even tire wear? If you do track, you need to check temperatures across the thread. I have a hard time to imagine that with -2.2 and -1.8 you would still have outside threadwear under street usage, unless you autocross...?... which is what I suspect you are setting up for.

 

Autox, with street driving to/from the site.
So I want aggressive autox settings.

Check for treadwear... lift the car up on a hoist, and look at the tires.
The rears were hardly touching the road on the inner 1" of tire surface.
Certainly were not rolling over from cornering.
I want to at least use the whole tread surface, so lowering the pressure
helped that... but still not enough... so let's put more camber in.

And as my friend/mechanic/racer says... forget what the numbers are,
go for visible results.