Looking to upgrade the wheels on my 3rd Gen. For sake of this math I'm just going to reference the stock size for comparison and not my newer aftermarket ones.

Stock 3rd Gen:

FRONT: 16x8 with 0mm offset = 115mm total backspace (4.5")
REAR: 16x8 with 16mm offset = 131mm total backspace (5.1")

Now given that almost no one makes wheels in those offsets anymore, I'm looking at running this set up with the common 2" spacers that are available:

FRONT: 18x9.5 with 32mm offset = 161mm total backspace (6.5") - 51mm spacers (2") = 115mm total backspace
REAR: 18x9.5 with 48mm offset = 182mm total backspace (7.1") - 51mm spacers (2") = 131mm total backspace

Am I understanding this concept of backspacing and offsets correctly?

FWIW, I would be running 275/35-18s all around with hopes of not rubbing, etc. Is there a sweet spot with offsets to have the benefit of a wider stance w/o the rubbing? Of course it would be great is companies made wheels in low offsets, but they don't anymore, at least without be cost prohibitive.

PS- Just to confirm, the wheel lug pattern is 5x4.75" (120.65mm)?

Thanks guys.

 

Having a 6.5" BS wheel with a 2" spacer on the front is going to give you 4.5", which will make the wheel stick out of the well about 1/2". Rear will be fine. A 1.5" spacer on the front will put you where you need to be.

Your math is wrong - you subtract the mm thickness of the spacer from the wheel offset - example: 32mm - 51mm = -19mm (or about the 1/2" I mentioned).

You have the lug pattern correct.

 

You see, I knew I was doing something wrong, which is why I asked.

Well I can have these wheels made with any offset between 22-62. What offset should should I choose? Thanks again!

 

With no spacers, you will need about 0 offset to sit right.

 

So with those sizes an offsets listed above it looks like this? -

F: 18x9.5 32mm offset + 1.5" spacers
R: 18x9.5 48mm offset + 2" spacers

As I mentioned though, the company will make them with any offset I want between 22-62, so if you have a more ideal set up to recommend, I'm all ears. Thanks again!

 

Why are you getting 4 wheels with the same diameter and width with 2 different offsets? Why not get 4 identical wheels so you can rotate them and use 4 of the same spacers?

I would opt for a hair more backspace, or positive offset. 0 offset will be 5.25" of backspace, it will fit fine. Since they wheels are 18" they will have more clearance to the strut body and the tie rod end, so using 5.5" of bs will tuck them under the car a bit more.

 

Well I have two options here for the 18x9.5 wheels . . .

1- (cheaper and already in stock): 35mm offset.

So what size spacers would I need for that?

2- (custom ordered): Can be had in any offset from 22 to 62.

I could also go to a 18x9 set up all around, but I'm trying to put down near 500hp.

Thanks for the help.

PS- Don't know if it matters much, but I'm currently running a Baer kit, but will likely go to one of EB Miller's 5th Gen kit or something.

 

Here are the custom sizes available:

18x8.5 ET10 - ET50
18x9.0 ET15 - ET55
18x9.5 ET22 - ET62
18x10 ET10 - ET50