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Discussion Starter #1
Im dumb and need help :LOL:

Ok, well right now I have a 6" BDS lift with nitto trail grapplers (35x12.5x20) on my stock 2010 20" rims. I have a 1/4" spacer in there at the moment to allow just enough room for the swing arm. I am looking at buying new rims specifically Rockstar XD that will push the tires out.

My question is can someone please explain backspacing/offset to me, so when i do go get these rims I will know something about what i am actually looking at and asking the dealer for.

thanks in advance
 

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Maybe this will help..


How to Measure Wheel BackSpace


Items required to measure wheel backspace:
Tape measure
Straight edge
Wheel w/o tire (preferred)

The easiest way to measure backspace is to lay the wheel face down onto the ground so the backside of the wheel is facing up. Take a straight edge and lay it diagonally across the inboard flange of the wheel. Take a tape measure and measure the distance from where the straight edge contacts the inboard flange to the hub mounting pad of the wheel. This measurement is backspace. The above photo shows three wheels with 2",3", & 4" backspace.



Measuring Wheel Offset

To calculate offset you'll need the following measurements:
Wheel backspace
Wheel Width
Wheel Center line (outboard flange to inboard flange measurement / 2) Subtract:
Wheel center line from Wheel backspace to get offset.
If backspace is less than the wheel centerline the offset is negative
If backspace is greater than the wheel centerline the offset is positive Tip:
To convert from inches to mm multiply by 25.4
To convert from mm to inches divide by 25.4




Backspace to Offset Conversion Chart The table on the right is q quick reference for finding offset, pick the rim width and follow the row over to the backspace of your wheel.

 

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or this....

Backspace and offset are two ways of describing where the wheel sits in relationship to the hub. As such, there is a relationship between the two making - it possible to convert from one to the other.

Backspacing is the easiest to understand. It is simply the distance from the back of the mounting pad to the back lip of the wheel. It is measured by laying the wheel on its face, placing a straight edge across the wheel, and then measuring down to mounting face. The higher this measurement the more the wheel is pushed inboard towards the car’s centerline, as shown in the illustration above.

Offset is the distance from the mounting surface to the centerline of the wheel, expressed in millimeters. Positive offset means that the wheels are pushed inboard towards the centerline of the car like a car with front wheel drive. Negative means that the wheels are moved outboard towards the fenders, widening the track.

TO CONVERT OFFSET TO BACKSPACING:

For positive offset wheels: (Wheel Width +1)/2 + (offset * .03937)

For negative offset wheels: (Wheel Width +1)/2 - (offset * .03937)

TO CONVERT BACKSPACING TO OFFSET:

Backspacing – (Wheel Width + 1)/2 * 25.4 = offset

Round this result to the nearest milimeter. If the answer is a negative number the wheel has negative offset, if positive then a positive offset.
 
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well first of all that is NOT a dumb question at all. I too and interested in this answer. I can't answer your question but wanted to let you know it isn't a dumb question.
 

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Discussion Starter #5
ok, thank you all for explaining that. That was the assumption i was under but i just wanted to make sure. I am looking for a negative offset to push my tires out away from the swingarm. appreciate the help
 

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Yes sir, no problem...negative is out, positive is in.
 

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Discussion Starter #7
one other question.... a -24mm offset pushes the wheels out about 4" is this what this means:

<LI class=wiki_listitem>-24mm Offset (4.5" backspacing)
 
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