Putting a 4" suspension lift on 06 TJ and wanted to do 33 12.5 15 as well and have them sticking out a couple inches from stock. Can someone help me with the whole offset/ backspace thing? I'm a newbie and would appreciate some help. Just to be clear it won't see extreme off road mostly pavement but would like to do mild off road occasionally. Thanks
Offset or backspace
- Thread starter cassius420
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Backspace and offset are directly correlated. Here's a little chart to show you the relation.
Typically you want about 3.5-4" of backspace to clear everything on a 33x12.50. Most common recommendation (and easy to find) will be an 8" wide wheel with a -19mm (ish) offset or 3.75"(ish) backspace.
Typically you want about 3.5-4" of backspace to clear everything on a 33x12.50. Most common recommendation (and easy to find) will be an 8" wide wheel with a -19mm (ish) offset or 3.75"(ish) backspace.
Thank you for clearing that up. So if I stay with the 8" rim and -19 offset I won't have any clearance issues? How far will that stick out from stock fender flares?
Assuming it's not a Sahara or Rubicon, probably 1-2". There's a lot of varying measurements on that as all tires measure a bit different and people measure from different spots on the fender and to different spots in the tire.
This is mine on 8" -19mm, with 33x10.5R15 BFG KO2s.
be aware that there are considerations beyond just the appearance that should go into selecting a backspacing. The farther the tire is out from the ball joints, the more difficult it becomes to steer at low speed, putting more stress on steering components, and amplifying undesirable road manners like the Jeep tracking to follow road irregularities and jerking to one side when that side hits a water puddle. It's generally advisable to run as much backspacing as you can get away with (keeping the tires as far in as possible), without so much as to cause the tire to contact things it shouldn't.
3.75" BS would definitely be safe from a clearance standpoint....I've never run 33x12.5 so I don't know what you can get away with from a clearance standpoint but I run 35x12.5 on 4".
Where Jeep wheels are concerned you can stick purely with the backspacing dimension which is more useful than the Offset where Jeeps and trucks are concerned. Offset is primarily for automotive wheels.
For a 12.5" wide tire 4" of backspacing is optimal and my first preference followed by 3.75".
The yellow tape measure is measuring the backspacing here... from the wheel's mounting flange to its inner-most edge closest to the suspension.
For a 12.5" wide tire 4" of backspacing is optimal and my first preference followed by 3.75".
The yellow tape measure is measuring the backspacing here... from the wheel's mounting flange to its inner-most edge closest to the suspension.
Offset and Backspacing are essentially two different measurements of the same topic.
Backspacing seems to be the 'older' measurement, whereas offset seems to be the 'new age' method.
As Jerry said,
From my short stint in the Jeep/Offroad world, it seems that most stuff for our jeeps are measured in 'backspacing'.
Either way, both are concerned with how much your wheel sticks OUT or IN your wheel well.
Backspacing is measured from the BACK of the wheel, and is a measurement of how far the wheel hub/face sit from the center-line of the wheel.
Offset is measured from the front side of the wheel, and is a measurement of how far the wheel hub/face sit from the back of the wheel.
Low 'offset' = High 'backspace'
High 'offset' = Low 'backspace'
In easy-theory, they're the same measurement concept, just measured from two different points of the wheel, and different companies seem to prefer one or the other for describing wheel specs.
Backspacing seems to be the 'older' measurement, whereas offset seems to be the 'new age' method.
As Jerry said,
you'll typically see 'offset' typically used more in aftermarket performance wheels, and 95% of what I messed with in the fast-car scene was measured in 'offset'.
From my short stint in the Jeep/Offroad world, it seems that most stuff for our jeeps are measured in 'backspacing'.
Either way, both are concerned with how much your wheel sticks OUT or IN your wheel well.
Backspacing is measured from the BACK of the wheel, and is a measurement of how far the wheel hub/face sit from the center-line of the wheel.
Offset is measured from the front side of the wheel, and is a measurement of how far the wheel hub/face sit from the back of the wheel.
Low 'offset' = High 'backspace'
High 'offset' = Low 'backspace'
In easy-theory, they're the same measurement concept, just measured from two different points of the wheel, and different companies seem to prefer one or the other for describing wheel specs.
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that's funny my mopar jk wheels are measured by offset. must be the automotive performance versions!
Offset and backspace are not directly correlated nor are they essentially the same thing.
One is a measurement of the mounting surface's offset from center. The other is a measurement of the distance of mounting surface from the back of the wheel.
These are two distinctly different measurements.
A 7" wide wheel with 4" backspacing has a very different offset than a 12" wide wheel with 4" backspacing.
I feel as though you just inadvertently agreed with everything I said.
As far as being 'directly correlated' ...
they are DIRECTLY correlated.
If you change your offset, you in-turn have changed your backspacing.
If you change your backspacing, you have also changed your offset.
There's not a wheel on this planet where Backspacing won't affect offset, and vise-versa.
They're the exact same measurement procedure, just standardized from two different points on a wheel.
(which is 100% up to manufacturer discretion)
Both measurements are essentially explaining the same thing, as long as you know the difference between the two.
BOTH are simply a way of letting you know how far IN or OUT your wheel will sit from the hub surface.
Technically speaking, all wheels have a set Offset AND Backspacing.
They are very much so in direct conjunction with each other.
Although only one measurement is actually needed in terms of marketing/purchasing.
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Offset is not the same measurement as backspacing. The two describe two different measurements. The two measurements are related to the extent that they describe where the mounting surface is from some point on the wheel.
Offset does not indicate backspacing. Backspacing does not indicate offset. There is no direct correlation.
But they are directly related to the wheel width. That's what the chart shows, each width wheel has a set offset and backspacing correlated.
No, as in an 8" wheel with a -18mm offset will always have 3.75" of backspacing. A 10" wheel with -18mm of offset will always have 4.75" of backspacing.
center of the wheel right? why is the offset of 0 of a 7" wheel 4" then? if the measurements were the same it would be half of 7.
Offset will be in millimeters, if you mean a 7" wheel with 4" of backspace, that would be because it has a 0mm offset.
Honestly, with this being written communication, I'm not sure if you're asking seriously or not. If you are, look at the chart I shared up above. It will show you what the offset and backspace will be for a wheel of a given width. If you know two of the measurements, you can find the third.
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