Need a spot check on my offset calcs (with Big Brakes)

[RYU]

I did some calculations and took some measurements for potential new 18" or 19" wheels. This will be going on a 1966 Chevelle with C6 Z06 brakes. I have the usual pro-touring suspension mods and will retain the inner fender wells and i'm not tubbed in the rear. Most of the wheels I shop for have ET (offset measurements) but I notice most of us here use the BS metric. I'm trying to convert to a proper ET measurement while also taking into account the BBK kit which is why i'm hoping for a 2nd set of eyes

The ideal max wheel sizing for the 66 seems to be..

F: 8" width @ 4.5" backspace (give or take .25")
R: 10" width @ 5.5" backspace (ditto)

Using an online calculator each of the above has ET 0 or 0mm offset.

I need to add increased spacing/thickness for both the front and rear Z06 calipers into the calc. Those things are thick.
F: +1.75" over the front hub section of the rotor
R: +1.5" ditto

Based on my calculations I need these widths.
F: 8" width @ ET45 or +45mm offset
R: 10" width @ ET35 or +35mm offset



Does that sound right?

[ProdigyCustoms]

The backspace will be the same no matter how much brake clearance you need. It is the pad thickness and spoke clearance that matters. What kind of wheels are you looking at? it will have to be something with a nearly 2" pad thickness to clear. most production wheels do not have nearly that tall a mounting pad which simply moves the center of the wheel outward meaning less lip on the wheel.

[RYU]

Hi Frank,

I will be using an aluminum wheel adapter. I current have a 1.75" F and a 1.5" R adapters on coincidence from a previous build but i'm not married to the idea. Custom wheels are just out of my price range right now so you're right... the tall mounting pad is needed which the spacers should account for.

[USAZR1]

I did some calculations and took some measurements for potential new 18" or 19" wheels. This will be going on a 1966 Chevelle with C6 Z06 brakes. I have the usual pro-touring suspension mods and will retain the inner fender wells and i'm not tubbed in the rear. Most of the wheels I shop for have ET (offset measurements) but I notice most of us here use the BS metric. I'm trying to convert to a proper ET measurement while also taking into account the BBK kit which is why i'm hoping for a 2nd set of eyes

The ideal max wheel sizing for the 66 seems to be..

F: 8" width @ 4.5" backspace (give or take .25")
R: 10" width @ 5.5" backspace (ditto)

Using an online calculator each of the above has ET 0 or 0mm offset.

I need to add increased spacing/thickness for both the front and rear Z06 calipers into the calc. Those things are thick.
F: +1.75" over the front hub section of the rotor
R: +1.5" ditto

Based on my calculations I need these widths.
F: 8" width @ ET45 or +45mm offset
R: 10" width @ ET35 or +35mm offset

Does that sound right?

What does ET mean? Can't say I've heard that term used before with wheel spacing. Anyway,a 10" wide rear wheel with +35mm offset equates to about 6.85" of backspacing. If your 66 isn't mini-tubbed,that much backspacing isn't going to work w/o spacers. With your 1.5" spacer,that number comes down to 5.35" or so;not enough bs. The total bs number I would shoot for on a 66-67 Chevelle or Elky w/10" rear wheel would be 5.75".

[ProdigyCustoms]

So you need BS of

Front 6 1/4 and rear 7"

[RYU]

that should come out to front ET45 and rear ET38. pretty close to my calcs. thank you!