im trying to find ssome wheels for my truck but i cant decide on an offset. im running 31x10.5 tires on a 15 inch rim and they rub a little bit when i cut it really hard. i was told they were rubbing the radius arm? anyways i was also told that a different offsset wheel would help with that. so my first question is what iss the stock wheel offset? also how much offset would i need to get them to keep from rubbing? i like the look of truckss when the wheelss sstick out from the fenders a little bit but not too much. anyone have pictures of their wheelss with different offsets and how much they stick out? i really want to see if 5inch offset iss too much or not so if anyone has ssome pics of those that would be great.
thank guys.

 

Backspacing is the distance from the back of the rim to the hub mounting surface, and the stock dimensions is 3.75" for 7.5" rims and 4" for the 8" version.

Offset is the distance the hub surface is from the centerline of the rim. Positive offset moves the wheel in under the vehicle(hub nearer the outer rim surface like the new trucks) while negative offset moves it out(hub nearer the inner rim). Stock offset is 0(zero) with the stock wheels.

With these trucks you want to keep backspacing at 4" or less regardless of rim width, any more will increase tire contact on the radius arm.

 

what would i do to get the tires to stick out more from underneath the fenders? offset or backsspacing? im kind of confussed now. i was under the impression that a greater backsspace would make the wheels stick out farther and not make it rub as much

 

More backspacing (per given width of the wheel) results in the wheel sinking further inboard. This is the same as more positive offset, per that same given wheel width. With those tires you got now you want at least east 8" wide wheels, maybe even more - assuming you go with 15x8 wheels you want 4" backspacing and that makes for 0 offset, but say you go with 15x10 wheels you still want the same 4" backspacing but now your offset is -1" cause the hub-mounting surface of the wheel is no longer in the middle of the width (which would be at 5" backspacing) but an inch inboard of there. Does that help any at all?

 

so a 3 inch backspaced wheel would stick out farther than a 5 inch back space?

ive got the aluminum wheels with the holes in them. are those the 8" wheels?

i believe that did help. let me get this right though. the backspacing is the space on the backsside of the wheel and the offset is the front side?

im new to trucks but i come from fourwheeler racing. we referred to wheels with their offsets. say you have a 5 inch wide wheel it may have 4/1 offset meaning one side is 4 inches deep and the other side is 1 inch deep.

 

If they are both the same width, then yes, that would be correct.

Honestly, they could be anything, as that design was and is still offered in a number of width options. Best way would be to measure it up yourself, or go to a tire place and have them grab their giant clamp-like measuring tool and do it for you.

Yes, and no - backspace is indeed the space on the inboard (back) side of the wheel, however offset is different. Offset has to do with where the hub-mounting surface is with respect to the center plane of the wheel. Let's go back to my 15x10 wheel example - the center plane of that wheel would be, as implied by its name, right across the middle of it, in other words if you were to cut the wheel across that plane the two halves you'd end up with will be both 5" wide, so the center plane of the wheel is 5" from either edge but for our purposes we'll use the inboard (back) edge of the wheel - so the center plane of this wheel is 5" from the inboard edge. Now let's look at the backspace, 4" there means that the hub-mounting surface is 4" away from the inboard edge. Compare this to the center plane, which is 5" away from that same wheel edge - this means the the center plane is an inch further outboard from the hub-mounting surface, or in other words the hub-mounting surface is an inch inboard of the center plane. Does that make sense?

Here's the approximate formula to determine what is what with cars and trucks:

(offset) = (backspace) - [ (wheel width) / 2 ]

So using the numbers for the 15x10wheel:

4" - [ 10" / 2 ] = 4" - 5" = -1"

The other way around:

(backspace) = (offset) + [ (wheel width) / 2 ]

And plugging in the 15x10 wheel numbers we have:

(-1") + [ 10"/ 2] = (-1") + 5" = 4"

 

ok i think i do get it now. thank you very much.

say i have two 10 inch wide wheels. one has 3" backspacing and the other has 5" backspacing. the 3" backspacing would stick out farther?

 

Yes, that is correct. You gotta watch out how far out they stick tho - too much and the tires may start catching the corners of the bumper and the fender wells, plus it also increases the load on the ball joints and the steering linkage, which will wear them faster.

 

tomorrow ill try and measure my wheel width. what is the recommended sizes? i want them to stick out a little bit but not a whole whoel lot. maybe 2 or 3 inches? would i rub the bumper or anything then? would that help me turn sharper? or atleast quit rubbing the radius arm?

 

Someone else will have to answer these questions for you man, as with a 2wd dually my setup couldn't be any farther from what you're working with there.

 

alright. thank you for all yoru help. ill wait for someone else to chime in i guess.

 

I would just leave it the way it is. The rubbing your talking about does not hurt anything, since its a a very low speed. I have 31 10.50 tires on my truck and consider this a non issue. The factory wheels look better than the aftermarket junk anyway. I had 15x8 offset wheels that stuck out a little more an the handling of the truck was not nearly as good. My truck looks and drives better with the factory 15x7.5 wheels.

I think this looks perfect.

 

Those are 15x7.5 wheels and are the best looking wheels for our trucks in my opinion. I wouldn't change it.

By the way having a wheel stick out 2-3 inchs is not a little its alot. It will also create more wear on the front end components.