Wheels: Offset, Backspacing, & Wheel Spacers

[05kfx]

HI guys NEW Here. I have a ? 4 ya. I have a 2003 Ford Sport Trac and would like to install some new wheels and tires. The current wheels are 16x7 and if you measure like above from the back of the wheel to the back rim lip, I come up with 4.5inches. Now I would like to install 22x9.5 wheels and a 2" lowering kit in the front and a 3" in the rear. Just wondering what you guys suggest i get for a offset of wheel. I AM LOST.. Also I DO NOT want the wheel to stick out of the wheel well. Thanks guys.. Casey

 

[pcunningham42]

Thank You!

Even I should be able to do this ..Thanks

 

[85gt]

I'd like to replace the wheels on my 06 Limited , can anyone tell me the factory 18" wheel offset ?
Thanks ,
Ronny

 

[rck2drums]

Sorry to bump this but are you saying that wheel spacers are bad or ok? I really want some but ifd they are dangerous then I don't. I can't be hauling around my family thinking my wheel might fly off.

 

[BonesDT]

I think you'll get mixed answers to that question.

If you want to go the safest route, get the spacers with their own lug bolts. This kind of spacer bolts onto your hub using your existing lug bolts, but then you need to chop off the excess length of the existing lug bolts and you install the tire with the new lug bolts welded to the spacers. The downside is that this is more permanent.

The cheaper spacers will just use your same lug bolts, putting stress too far out on the end of the lug bolts.

 

[JCUZ]

I think you'll get mixed answers to that question.

If you want to go the safest route, get the spacers with their own lug bolts. This kind of spacer bolts onto your hub using your existing lug bolts, but then you need to chop off the excess length of the existing lug bolts and you install the tire with the new lug bolts welded to the spacers. The downside is that this is more permanent.

The cheaper spacers will just use your same lug bolts, putting stress too far out on the end of the lug bolts.

Lug bolts (or wheel studs) do not take the weight of the wheel, the centre hub adapter does that (or should). Wheel spacers that do not have a machined lip to support the centre of the wheel will mean that you break wheel studs.

 

[BonesDT]

Lug bolts (or wheel studs) do not take the weight of the wheel, the centre hub adapter does that (or should). Wheel spacers that do not have a machined lip to support the centre of the wheel will mean that you break wheel studs.

Good point. I forgot about that. Definately a must when buying a spacer.

Come to think about it, I don't think my new American Racing wheels rest on the center hub! I should look into that.

 

[Richie18]

The relationship between wheel back spacing and offset on here does not work for me when using numbers given by a website for any of their wheels.

 

[storlied]

bump

 

[Richie18]

Anybdoy have any info on this?

 

[storlied]

Guess not, or we missed something... I think the Offset is half of the BS.. with some conversion?.. I don't know...

 

[FROADER]

Guess not, or we missed something... I think the Offset is half of the BS.. with some conversion?.. I don't know...

To calculate offset is even easier, measure the wheel's overall width, subtract its backspace measurement, and divide that by two. You're done.

.

 

[rwenzing]

The relationship between wheel back spacing and offset on here does not work for me when using numbers given by a website for any of their wheels.

The important thing to keep in mind is that a wheel's backspacing and its nominal width are not measured to the same place. This is what usually causes the confusion.

Width is measured to the inside of the flanges where the beads seat.
Backspacing is measured from the outside of the inboard flange to where the wheel mounts.

As a rule of thumb, most wheel flanges are very close to 1/2" thick each. So the overall width of a nominal 7" wheel is about 8".



Example: The offset of a factory Gen 1 or 2 Explorer wheel is +12mm, close to 1/2".

To find the backspace dimension of a wheel with a 7" nominal width and +12mm offset, start with the overall width (7" + 1" = 8"), divide by two and then add the offset (8"/2) + 1/2" = 4 1/2"



Pictures of a wheel with same dimensions as in the above example. notice that the measurement is being taken from innermost part of the inboard flange to the wheel's mounting surface. This is where the overall width is about 8" as opposed to 7" where the beads seat.

This is a good cross reference for offset, width and BS:

 

[Richie18]

Thanks for the clearing things up.

 

[Explorer_Phil]

Rims Question

Ok, so, after reading all this great information, I feel as though I get the concept, but can't apply it.

I am looking at getting new rims for my '01 Sport and can't figure out if I need the 4.5" or the 3.75" backspacing. I am going to get 15x8 rims and put 31x10.5x15 tires on them. I would rather not accidently destroy my bearings or something, so any help on this would be appreciated. Thanks!

 

[storlied]

3.75 for 15x8

 

[corkey]

and for 15x10 ??

is it 4 inches ?

 

[bill55az]

Alloy wheels usually have the offset cast into the inside of the rim, example is 16x7x12, where 12 is the offset and using the chart shown in a previous post, that means 4.5" backspacing on a 7" rim. If you have deep backspace and want to move the tires AWAY from the truck, go for less backspace. Again use the chart, there is negative and positive offset listed.

 

[Jd0gg919]

I'm looking at a set of 17x9 wheels with 4.75 BS and -6mm offset. Could i run 33's with minor trimming? I've already got a 3in B/L, TT and shackles with 32x11.50x15 on the stock rims. I've read through this thread but it didn't really show different applications it only showed me how to calculate it. Preciate any answers.

-Justin

 

[SubLo]

Hi guys. Kind of new'ish here but a long time Interweb and forum veteran elsewhere. One of those places is LegacyGT.com as I also have an '06 LGT Spec.B. I bring this up in the wheel/tire area here because I'm shopping new 18's and Nitto Terra Grappler 255/55/18s.

Lots of great info here particurlarly in this thread but it's not specific to our trucks. If any of you have the kind of experience, perhaps you work at a tire shop , that is detailed for my other car here: http://legacygt.com/forums/showthread.php?t=4426, it would be fantastic if you could graciously share with me and everyone else on here.

Another one of my favorites there, which I think could be really useful to Exp wheel/tire shoppers is this one http://legacygt.com/forums/showthread.php?t=19741, a compilation of pictures of installed shoes.

Yep. I've searched exhaustively and there is some information quite scattered about here and I'm still having trouble finding exactly what I'm looking for.

<flame on>