offset help needed 3 pc wheels

[kosta]

ok it's a problem
anyone who can help, i truly appreciate it

my original wheels were hre 3 piece
front 19x8 et 31
rear 19x9 et 43

then they shaved 3mm off of the back hub area

then swapped the inner barrels to make them all 8.5 wide
the fronts and centers remained the same

what would the new offsets be?

front 19x8.5 et??
rear 19x8.5 et??

[NONN37]

although im not 100% sure this is correct. heres my attempt at this word problem. Maybe you can compare it to other members results.

front +40.35mm
rear +39.65mm

I guess you can say theyre both about 40.

[kosta]

the hre rep said the 31 went to a 40
and the 43 went to a 37

not sure

[SizeItUp]

the front makes sense 19x8 +31 shave off 3mm gives you a +28 and then they added the .5 inch barrel, 12mm which would give you +40.

the rear i dont get with a 19x9 +43 shave the rear 3mm gives you a +40 take away .5 inch barrel should be around +28. when you change the whole wheel usually the .5 inch is split in half. 6mm to the front and 6 mm to the rear. unless they changed something else on the wheel

[kosta]

so maybe his calculation was wrong?

[Digitalwave]

Shaving 3mm means it adds 3mm to the offsets, so ET34 and ET46 respectively. I don't know about the remainder of the calculation.

[kosta]

still having difficulty with this

ok so i know so far the shaving adds +3
so 31 is now 34 and 43 is now 46

also i know when changing the barrels 1/2 inch
that changes approx 12.7 mm

however since the offset is measured from the hub to the center of the wheel, what is the calculation?

[kosta]

any1?

[Digitalwave]

Front: ET40.5
Rear: ET39.5

Here is how I came to the conclusion:

In the front, shaving 3mm makes it ET34. Adding .5" to the rear barrel adds ~6.5mm to the offset, making it ET40.5.

In the rear, shaving 3mm makes it ET46. Removing .5" from the rear barrel substracts ~6.5mm, making it ET39.5.