Offset question?
#1
#4
Where did you get those specs from? You can figure the backspacing on a wheel by using the following chart. Just line up the wheel width with the offset to determine backspacing:
![](https://www.rsracing.com/images/tech-wheeloffset.gif)
Unless I'm completely wrong, you can't have two wheels of the same size with different offsets, have the same backspacing (5.17 as listed in the above specs you posted).
According to the chart the first wheel 18x9 with 30mm offset would have a backspacing of approx. 6.25" and the second wheel, 18x9 with 18mm offset would have a backspacing of approx. 5.7".
I think the first one with the greater backspacing may possibly rub your spindle so it probably wouldn't work, and the second one I believe would stick out about 1.3" further than stock.
If I'm wrong, I'm sure someone else who knows more about this will correct me.
This is assuming you're talking about the '04 and up model F150.
![](https://www.rsracing.com/images/tech-wheeloffset.gif)
Unless I'm completely wrong, you can't have two wheels of the same size with different offsets, have the same backspacing (5.17 as listed in the above specs you posted).
According to the chart the first wheel 18x9 with 30mm offset would have a backspacing of approx. 6.25" and the second wheel, 18x9 with 18mm offset would have a backspacing of approx. 5.7".
I think the first one with the greater backspacing may possibly rub your spindle so it probably wouldn't work, and the second one I believe would stick out about 1.3" further than stock.
If I'm wrong, I'm sure someone else who knows more about this will correct me.
This is assuming you're talking about the '04 and up model F150.
Last edited by Copenhagen848; 11-25-2007 at 11:20 AM.
#6
Ok, I just checked the specs on those wheels, and it looks like the 18x9 come in the offsets of -12mm and 18mm.
The -12mm will give you a backspacing of 4.5" and the 18mm will give you a backspacing of about 5.7" like I said before.
I'd go with the 18mm offset, the -12mm offset will stick out quite a bit further than stock.
What year/model (4x2 or 4x4) will these be going on?
The -12mm will give you a backspacing of 4.5" and the 18mm will give you a backspacing of about 5.7" like I said before.
I'd go with the 18mm offset, the -12mm offset will stick out quite a bit further than stock.
What year/model (4x2 or 4x4) will these be going on?
#7
I have a 2005 STX 4X2 that I want to get a leveling kit put in and then upgrade to XD Monsters with tires that dont stick out too far. I dont like the low profile tire look but I dont want the mudder tire look either.
I want a look that is an A/T larger tire with Monsters that stick out around an inch or so.
I am clueless when it comes to this stuff.
I want a look that is an A/T larger tire with Monsters that stick out around an inch or so.
I am clueless when it comes to this stuff.
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#8
To give you an idea of how far your tires will stick out on the Monsters, take a look at my gallery, I have a side shot.
My wheels are 18x8.5" with 5.75" of backspacing. My suspension lift increased the track width of my front tires by about .5", therefore the Monsters would stick out about the same as my front tires I believe.
My wheels are 18x8.5" with 5.75" of backspacing. My suspension lift increased the track width of my front tires by about .5", therefore the Monsters would stick out about the same as my front tires I believe.