Is offset the same as backspacing?

 

No. Backspacing is the distance from the wheel mounting surface of the wheel to the innermost aspect of the wheel, whereas offset is the distance in mm from the center of the rim (ie 4.5" on a 18x9" rim) to the wheel mounting surface. The two are related, but not the same.

https://www.rsracing.com/tech-wheel.html

Has a pretty good explanation with pics/diagrams. A good read.

 

Right.

 

okay!

So the backspacing of my 17" stock wheels is 4.5". Anyone know what the offset is?

Preesh!

 

How wide is the wheel? Basically, take the width of the wheel and divide by 2. Then add your offset. That's your backspacing.

 

No, the OEM 17 and 18 inch wheels on the 04-07's are 7.5 inches wide and they have 5.5 inches of backspacing.

 

I know the backspacing....How do you find the offset then?

Right. So whats the offset of the OEM 17" then wandell, tire and wheel guru!!!

 

I'm not good with offset, it's just harder to understand and visualize than backspacing.

 

If the wheel is 7.5", half is 3.75". The different between the backspacing (5.5") and half of the wheel (3.75") is the offset (1.75"). 1.71" in MM is about 44.5 mm. This is the part I always get fuzzy on, whether it's + or - spacing. I believe that if more wheel is to the inside (center of truck) it is - spacing, so the stock wheel has -44.5 mm offset. Of course with a wider wheel, the offset changes - but the backspacing does not.

I'm with Wandell, backspacing is easier to make sense of and is necessary for selecting the right wheels - if the stock wheel is 5.5" backspacing, you really want to stay in that area... more backspacing and you start hitting the frame when turning, less and the stress on the bearings and ball joints goes up. 4.5 - 6 is probably a good range to stay in.

Offset tells you where in relation to the centerline of the wheel the hub face falls - but then you need to know wheel width and calculate to get the rest done. With backspacing, there's less numbers to play with... a 10" wheel with 5.5" of backspacing puts 4.5" in front of the hub. Simple!