Rim Offset - How to measure it and get it right

I answered this in a thread and thought i would put it here for all to view, hope it helps.

Firstly this is a Nissan Patrol Forum so note that the standard offset on a Nissan Patrol is +10 or positive 10.

Your offset choice will determine where the wheel sits in your wheel arch and whether it stick out of your guards at all.

On a Nissan Patrol it is very common to increase the offset into the Negative to bring the wheels further out to the edge of your wheel arches to give a wider track and stop bigger tyres from scrubbing on the inner guard.

OK so to get the right measurement you are really going to need a rim off the car or your spare off the door if it is the same. You need to measure the back space of the rim centre to figure out the offset. Offset equals how much the centre of the rim is away from the middle of the rim...

from the diagram below you can see how important it is to know the exact width of your rim. stop into a tyre joint and they will throw a calliper on it for you if you have time or you can figure that out.

Once you have the width of the rim then you halve it to determine the centre of the rim. Offset is how far from the centre of the rim is the centre mounting plate.

OK. You need to lay something across the back side of the rim outer edge of the bead to outer edge of the bead. Then measure the distance from that line to the back of the centre plate of the hub to determine where it is in relation to the rolling rim.

on an 8 inch rim i think they are 200mm wide (you should measure to make sure as every rim is different). zero offset would measure 100mm. Negative 22 offset (considered Toyota offset by most) would measure 78mm to the back plate. Standard Nissan offset of +10 would measure 110mm to the back plate.


Attachment 69812

^^^^ Now that is a pic of an Alloy Mag wheel. the front of the rim is to the left of the pic and the back is to the right.

or we can get a little technical ;)

Attachment 69813

Attachment 69814

Attachment 69815

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


An that is that.. Hope that helps you.

Cheers MR

i get my new tyres this week
so while the rims are bare im gunna measure them up
thanks mate the more i read on this forum the more i learn or in most cases get totally confused hahahahahaha...roflmao

Great information MR, we'll sticky this one for sure!

Quote:

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Originally Posted by MudRunnerTD

Firstly this is a Nissan Patrol Forum so note that the standard offset on a Nissan Patrol is +10 or positive 10.

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Only if we are talking 8" rims.
The offset for 6" rims is +30, so when talking offset, it is important to also note the width that it relates to.
What the difference in offset does for the different rim widths, basically makes the backspace the same (approximately 123mm vs 120mm).

Very confusing when people talk of Toyota offset and Nissan offset.

Quote:

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on an 8 inch rim i think they are 200mm wide (you should measure to make sure as every rim is different). zero offset would measure 100mm. Negative 22 offset (considered Toyota offset by most) would measure 78mm to the back plate. Standard Nissan offset of +10 would measure 110mm to the back plate.

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Not quite.
The rim width is the internal distance between the beads. The nissan 16x8 steel GU rim is 203mm between the beads, and approximately 230 from outside flange to outside flange overall, which is the measurement you need.
Using these numbers (230mm),
zero offset is a backspace of 115mm
-22 offset is a backspace of 93mm
+10 offset is a backspace of 125mm

When I measured up some GU 16x8 steel rims, I had a backspace of 123mm which calculated the offset as +8.

When looking at alloy rims, while the rim width will be the same between the beads(for the same rim width obviously), the flange width tends to be thicker than steel rims, so for the same offset, the measured backspace is larger, or to keep the backspace the same, you have a lower offset.

The easiest way to measure the offset without having to even know the rim width is to measure the distance from outside edge to face and from inside edge to face and halve the difference

thanks for the above info MR
i have a question? i measured my offset this afternoon and i got a measuremnet of 101mm from the bead to the front side of the mounting plate and 95 from the bead to the mounting plate on the back side?? would this mean i have almost a 0 offset??
my next question? would this be an ok offset to run a 33 12.5 tyre oh and its a 15x8 rim.

thanks
Gav

Quote:

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Originally Posted by gavinsell

thanks for the above info MR
i have a question? i measured my offset this afternoon and i got a measuremnet of 101mm from the bead to the front side of the mounting plate and 95 from the bead to the mounting plate on the back side?? would this mean i have almost a 0 offset??
my next question? would this be an ok offset to run a 33 12.5 tyre oh and its a 15x8 rim.

thanks
Gav

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You need to measure through the centre hole to the back mounting face for the front offset to be accurate. The thickness of the centre plate must be measured as part of the front measurement. Measure again. You have the back side so you should be able to get the front with the wheel on the car if you have put it on already.

Quote:

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Originally Posted by MudRunnerTD

You need to measure through the centre hole to the back mounting face for the front offset to be accurate. The thickness of the centre plate must be measured as part of the front measurement. Measure again. You have the back side so you should be able to get the front with the wheel on the car if you have put it on already.

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make that 107...
Thanks MR

Thanks MR,

Thanks M/R for the great info.

I was wondering if the offset is also stamped into the back of the alloy rim.

I have performance alloy rims (Storm 17x8s) that have stamped (next to the size) ET 0.

Now, I was told that these rims were neg13 offset when I purchased them, but according to the original supplier/importer they only supplied them in a zero offset.

I haven't measured them as per your first post yet (yes, I am lazy :o ) as usual I am trying the easy way first.

Cheers Rodney