Backspace vs Offset
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Here's a good read on that topic!
http://www.eastwoodco.com/jump.jsp?i...8&iSubCat=1441
Pro
Joined: Feb 2005
Posts: 571
Likes: 0
From: Harleysville pa
That is correct. To me backspacing is the old way of determining wheel depth and offset is the newschool way.
Back space = Distance from the back side of the rim to the mounting area.
Offset = The distance from the center of the rim to either a positive offset or a negitive offset. Positive would me from the center to the face of the rim and negitive is from the center of rim to the back.
Hope this helps.
Back space = Distance from the back side of the rim to the mounting area.
Offset = The distance from the center of the rim to either a positive offset or a negitive offset. Positive would me from the center to the face of the rim and negitive is from the center of rim to the back.
Hope this helps.
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
No, this wheel is not at zero offset.
Wheel width specifications are measured from the INSIDE of the rim. If you measured your 8 "wheel from the outside edges you would find it is roughly 9" wide. Backspacing is measured from this OUTSIDE edge to the mounting face of the wheel.
You would need 4 1/2" of back space for a zero offset wheel. This means your wheel with 4 inches of backspacing has one half inch of offset.
Wheel width specifications are measured from the INSIDE of the rim. If you measured your 8 "wheel from the outside edges you would find it is roughly 9" wide. Backspacing is measured from this OUTSIDE edge to the mounting face of the wheel.
You would need 4 1/2" of back space for a zero offset wheel. This means your wheel with 4 inches of backspacing has one half inch of offset.
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
That is correct. To me backspacing is the old way of determining wheel depth and offset is the newschool way.
Back space = Distance from the back side of the rim to the mounting area.
Offset = The distance from the center of the rim to either a positive offset or a negitive offset. Positive would me from the center to the face of the rim and negitive is from the center of rim to the back.
Hope this helps.
Back space = Distance from the back side of the rim to the mounting area.
Offset = The distance from the center of the rim to either a positive offset or a negitive offset. Positive would me from the center to the face of the rim and negitive is from the center of rim to the back.
Hope this helps.
Backspace is measured by putting a flat edge across the backside bead (where the tire bead hits the wheel) and measuring vertically down to the mounting flange.
Melting Slicks
Joined: Jul 2005
Posts: 2,545
Likes: 3
From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
That above description is correct. Consider the mounting flange that goes against the brake rotor. If this flange is dead center in the vertical plane of the wheel, it's 0.
Backspace is measured by putting a flat edge across the backside bead (where the tire bead hits the wheel) and measuring vertically down to the mounting flange.
Backspace is measured by putting a flat edge across the backside bead (where the tire bead hits the wheel) and measuring vertically down to the mounting flange.
excellent answer SanDiegoPaul
Racer
Joined: Oct 2000
Posts: 491
Likes: 12
From: Los Altos Hills, CA
Guys, I hate to swim upstream on this issue, but this is NOT a zero offset wheel.
Backspacing is NOT measured from the "backside bead", it is measured from the backside edge of the wheel. That is, it is not measured from where the tire bead hits the wall, but from where the inside edge of the wheel sits. The difference between the backside bead and the backside edge of the wheel is the thickness of the wheel lip and it is typically 1/2" (12mm).
To measure backspacing, lay the wheel flat with the mounting face facing up. Lay a straight edge across the rim and measure the distance from the rim to the mounting face.
Here's a website with pictures and definitions of offset and backspace:
https://rsracing.com/tech-wheel.html#backspace
You can also go down to their "backset to offset conversion chart" for a quick answer.
I find backspacing to be a more useful definition than offset as it describes how much the wheel sits inboard from the tire mounting face.
Backspacing is NOT measured from the "backside bead", it is measured from the backside edge of the wheel. That is, it is not measured from where the tire bead hits the wall, but from where the inside edge of the wheel sits. The difference between the backside bead and the backside edge of the wheel is the thickness of the wheel lip and it is typically 1/2" (12mm).
To measure backspacing, lay the wheel flat with the mounting face facing up. Lay a straight edge across the rim and measure the distance from the rim to the mounting face.
Here's a website with pictures and definitions of offset and backspace:
https://rsracing.com/tech-wheel.html#backspace
You can also go down to their "backset to offset conversion chart" for a quick answer.
I find backspacing to be a more useful definition than offset as it describes how much the wheel sits inboard from the tire mounting face.
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