Suspension vs Wheel Size & Offset
 

I'm wondering if a Camaro 2.0T with 18x8.5 32mm offset wheels from the factory and a Camaro 2.0T with 20x8.5 25mm offset wheels from the factory have identical or different suspension setups?

:noidea:

Yes, they should both have identical suspensions (FE2 RPO code). Only time a 2.0T camaro would have different suspension is if it's a 1LE.

I don't understand the reason that the 18" and 20" offsets are different, when the width of the wheels are the same? I thought the diameter is unrelated to the offset.

The offset is independent of the diameter. The lower offset (given the same width) will push the wheels out further for a more aggressive stance.

I understand, so from a performance aspect, is the higher offset (if the diameters were equal) better because it brings the wheels in?

To figure out why the offset is different, you need to look at the OD of the 18" and 20" setup. If they are the same OD the offset would be the same for both. But if the OD is different, the change in offset will help maintain the desired scrub radius.

If wheel diameter doesn't affect offset, why does tire diameter affect it? Is it a matter of clearance?

The 18" setup's tires (245/50-18) have an OD of 27.6457".

The 20" setup's tires (245/40-20) have an OD of 27.7165", or about 0.07" different from the 18" setup.

That's pretty close.

It could possibly be a brake clearance thing? 20s are meant to fit the SS package with the 4-piston Brembos, and I'd assume that brake package requires more room than the base floating caliper on the LTs.

Wheels pushed out more just look better.
GM wants to give you a reason to upgrade your wheels when you buy the car.

Yes, it makes sense, but unfortunately it affects the scrub radius.

If you want the outside face of the wheel to stay in the same spot when you go to a wider or thinner wheel, the offset must change to keep the mounting interface at the same place with the hub face.

Pretend this is the top down view of your front left wheel and you want to keep the outside (left) edge of either wheel flush with the fender.

|----i------|
|----i----|

On the thinner wheel the offset is 0 (middle), but to keep that front left wheel at the same outer position, the wider wheel needs to move the offset away from the middle.

I understand that part. It seems that one must choose between appearance and handling when choosing aftermarket wheels because of the scrub radius. The wheels sitting further out look better but it affects how the car handles.