[Summit1le1ss]

So before I try this, has anyone tried the 11 rear wheel with 305s up front?
I would love a square setup with the factory wheels.

[backhill]

The inner clearance from the wheel to the strut will shrink by 36mm. I don't know what the current clearance is with the 10" wide wheel. You would need to find a custom wheel that's 20x11 wheel with a ~20mm offset AND add a 10mm spacer on the front.

Factory numbers For reference:
Front: 20x10 et 20mm
Rear: 20x11 et 43mm

[Summit1le1ss]

I'm gonna pull them off next weekend to clean and coat them, so I will take some measurements.
Appreciate the info.

[backhill]

Forgot to add: the wheel will also stick out another inch further than the current 10" with my recommendation, or ~ 0.5" without the spacer, but I don't know if it will clear the strut.

[Summit1le1ss]

Well, I'm impatient... So looks like needs about 1.5" spacer to clear strut. Sticks out way too far. Back to drawing board.

[BradfordCamaro]

Stick the 10's on the back. Done.
There is your square setup

[backhill]

Originally Posted by Summit1le1ss

Well, I'm impatient... So looks like needs about 1.5" spacer to clear strut. Sticks out way too far. Back to drawing board.

Out of curiosity, what is the clearance in front with the 10" wheel? If you need 1.5" for the 11", sounds like the front is hairs away from the strut. My math tells me based on your observation that the clearance is 12-14mm

[backhill]

Originally Posted by BradfordCamaro

Stick the 10's on the back. Done.
There is your square setup

Agreed. Your best bet will be to keep 10" on the corners. They'll have almost an additional 2" of clearance in the rear. However, the rears will stick out 10mm more than the 11" OE wheels.

I think this would help reduce the mild understeer that the magazines are claiming.

[Summit1le1ss]

Originally Posted by backhill

Out of curiosity, what is the clearance in front with the 10" wheel? If you need 1.5" for the 11", sounds like the front is hairs away from the strut. My math tells me based on your observation that the clearance is 12-14mm

Unsure as I didn't measure. I had two 25mm spacers, bolted them together and tried to put rear wheel on... No go. Hits caliper, so I stopped. I could only eyeball it as I'm by myself right now. Looked about 1/2 off. With the factory 10, I'd say 5-8mm clearance from caliper and strut is about correct.

I thought about 10 inch rear, but I want 11 inch with 305s..

[bub]

2013 - 2015 Gen 5 1LE wheels (or MRR 228's for the Gen 5 1LE) and offsets with 285's will square it as well without spacers and without extensive protrusion outside the fenders.

That's what our winter set is, but with BFG all season (A/S) tires for winter.

Does feel looser in the back end running this set up. Not sure if it is attributable to the 285 vs. 305 rear or, more likely, the A/S compound.

[V1LE8R]

I have the oem z28s. Im going to try for a 305 up front. Offset is 11mm. After plugging in the numbers it'll move it .1 inches (3.7mm) closer to the inside. Im optimistic it'll fit.

[Egon]

Although it is outside of mfg specs it is possible to run 305's on a 10 in wheel. Last years second place at SCCA Nats for F-Street, Courtney Cormier ran a 5th gen on a 305 square setup, the front tires were on the stock 10 in wheel. Ryan Otis, first place in FS at Nats runs 275s on the stock front 8.5 in wheels on his 2016 Camaro SS and he came in first place. (stock max for 8.5 is 255)

I have to ask though what is the motivation to go to a square setup?

[backhill]

Originally Posted by V1LE8R

I have the oem z28s. Im going to try for a 305 up front. Offset is 11mm. After plugging in the numbers it'll move it .1 inches (3.7mm) closer to the inside. Im optimistic it'll fit.

It should. Throw pics up when you get them on.

[backhill]

Originally Posted by Egon

I have to ask though what is the motivation to go to a square setup?

The advantage is two fold:

1) Being able to rotate your tires and get more life and track days out of them. I'd much rather be able to switch from left to right than front to back, and you can do that with a staggered setup. That said, it's also nice to be able to take your worst tire and stick it on the corner that sees the least load, can't do that if your worst tire is a rear and it won't fit on the front. There aren't very many track tires that are directional unless you're using them in the rain and that's just for performance, not safety. I've used R888's backwards in the rain before, for instance. Not really a big deal.


2) In a quick, simplistic terms, a square setup reduces understeer if you are adding more rubber to the front, or conversely, removing rubber from the back. This is situational based on car, suspension, tires, etc. It also depends on if the rear is set up to track directly behind the front wheels. If the general balance of the car has oversteer (ie: Porsche 911), then it may give too much oversteer on an already turn-in-happy car.