Back spacing/offset conversion question
Back spacing/offset conversion question
I was wondering if anyone knows if 20x9 wheels with a 6.5" backspacing will fit with out fender modifications on our cars. Backspacing is a new concept to me, but it looks like the proper way to convert backspacing into offset is to subtract the centerline from the backspacing measurement and multiplying by 25.4.
I guess the main part of the equation I am missing is the centerline. Does anyone know what the centerline is on a 20x9 HRE wheel?
Thanks
I guess the main part of the equation I am missing is the centerline. Does anyone know what the centerline is on a 20x9 HRE wheel?
Thanks
Lexus Champion
Joined: Feb 2002
Posts: 4,466
Likes: 14
From: Cali
It's 20x9 +38 for the short answer. This will fit the GS well.
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
Lexus Test Driver
Joined: Mar 2002
Posts: 1,248
Likes: 0
From: Maryland
Damn.....
It's 20x9 +38 for the short answer. This will fit the GS well.
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
Bob,
You are the man!
-Joe
Lexus Fanatic
Joined: Dec 2003
Posts: 14,523
Likes: 3
From: new jersey
It's 20x9 +38 for the short answer. This will fit the GS well.
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
You are the man Bob
It's 20x9 +38 for the short answer. This will fit the GS well.
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
I did that in my head... (aren't I great?)
The thing most people miss with these calculations is the rim flange thickness.
A 20x9 wheel is the bead-to-bead measurement... you have to add in the
thickness of the beads to get the true centerline. The HREs are 1/2" per side.
Breakdown:
20x9 + 1/2 + 1/2 = 20x10 (overall width)
20x10 / 2 = 5" (centerline)
backspacing 6.5" - centerline 5" = 1.5" (this is the "offset" number in inches)
1.5 X 25.4 = 38MM final offset number
Thank you sir! As I was writing the thread, you specifically came to mind. I estimated 1/2" per side, but really wanted to make sure.
Thanks again, you the man
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