2010FX4F150GILROY

I will see if I can say this better,,,, half of 9 is 4.5 thats the center of the wheel. So any offset thats more then 4.5 either direction means the mounting flange sits beyond the edge of the rim... So it would look like it does on a dually where the center of the wheel sticks out past the edge of the rim...

Paxford

After seeing the link I see where your going with this. Using the calculator it shows my aftermarket wheels (17 x 9 -6 offset, 4.75 bs) are 49 mm farther out (a little over 2 inches) from the stock wheels (17 x 7.5 -24 offset, 5.75 bs). They are also 11 mm farther out from the inner clearance compared to stock wheels (about 1/2 inch). Even though my rim moves offset out 1 inch, it ends up with 2 inches on the outside and 1/2 inch on the inside (for net 1.5 inches) because the rim is wider (by 1.5 inches) overall compared to stock.

I think your on the right track in using this tool to analyze this, but I am not sure if your starting point is correct (ie. oem rim measures). 17's and 18's are 7.5 inches wide, 20s are 8.5 inches wide. As for offset/backspacing I only know the 17's are -6/5.75. I suspect the 18's and 20's are somewhere in that range though.

bump for more pics?

2010FX4F150GILROY

I awsnot really going anywhere just using math and measurements.. I used 9 as my wheels I have now are 9 so 4.5 inch either direction is the outside edge of wheel, becuase 4.5 is the center.. Just thats what I get from the calculator?

Paxford

I guess I am just still wondering what your getting at here ... that stock back space is 4.5 ?

I am seeing the centerline considerations. So on a 9" rim 4.5" would be dead nuts center, and any deviation would be positive or negative offset. So 4.75" back space would be a deviation from 4.5" in the amount of .25, which equates to -6 mm, or -6 offset (negative because we are bringing the mounting surface in, not out).

I guess with a 10" wide rim it would be 5" dead nuts center, and 5.25 backspace would result in -6 offset too. Makes sense ... kinda. I dunno.

dootech

I'd like to bump this thread cause you guys are effing hilarious. Offset and backspace is not the same thing, I just don't see what's difficult about it.
Let's take my stock rims 18x7.5 +44 OS (09 xlt).
Hypothetically I dismount tire and lay rim on ground chrome side down. Put straight edge across rim and measure from the inside hub flange to the bottom of straight edge should be just about 5.5".
The thing you guys aren't getting is that offset doesn't change, but backspacing is dependent on rim width AND offset.

Example so my stock rim (18x7.5 44offset) has a backspace of 5.5".

Fictitious wheel 20x10 with 5.5" backspace. What is the offset? If you said 44 you're effin wrong. Wheel center line is 5" from back so figure the hub flange is .5" further out from center line. Convert .5" to mm.... .5x25.4=12.7 This wheel would probably be listed as +12 offset

Paxford

Makes sense. After the last comment (in June) I figured out what you are describing (in that bs varies based on rim width and os), hence no more discussion. Actually the discussion was off topic in the first place, the intent of the thread was to get pics of the newer trucks with rims measuring -6 os, 4.75 bs and 17 X 9 ... which still hasn't happened. This is surprising to me given the fact that all Pro Comp rims in the 17 X 9 size for our trucks have this os and bs. Welcome to the forum. You gotta pic?

Paxford

And I should have identified 17 X 9 in my first post, but I doubt there are any rims out there for our trucks with -6 os and 4.75 bs that aren't 17 X 9.

wvbrett

Hey Pax, do you have any pictures of your wheels/tires? I am about to jump on the same setup except the chrome one (6005) and was wondering what it looked like sticking out.