The full understanding of backspacing.

[nsaladino]

Ok, so I've read a ton of posts about backspacing, and I have a pretty good Idea on what will fit per application(lifted vs not lifted) but a few things eluded me in my searching. So basically what I got from everythign I read was that the back spacing your looking for is going to be < 4.75-4.5 but I've found a few wheels that I really like with a 0 backspacing, so would that even fit? Basically what is the permittable rang of backspacing, and then what sized tires would you be able to fit with the different backspacing, lets say on a stock truck or a leveled truck(2-2.5 raise in the front.) Maybe we can get all the info together therefore going forward we will have a place to send all BS questions. If there is already a post reguarding all this info then I apologize for wasting anyones time but in the past few weeks of searching I was unable to find it.

[Comattack]

Maybe this will help.
You probably already know this, but in case someone else doesn't, backspacing is the distance from the inside lip (rotor side) of the wheel to the surface that bolts up to the axle (mounting pad).

More backspacing puts the wheel closer in toward the frame, shock, & steering components.
Less backspacing puts the wheel farther away from them.



If you plan to add larger, wider tires, you will need to move the wheels/tires farther away from the shock & steering components to reduce rubbing. So when you lift it and go to wider tires, it's critical to use less backspacing to move the tire out farther to avoid the springs and/or control arms when turning and flexing. You do this by reducing the backspacing. At a minimum, you should reduce the backspacing an amount equal to HALF of the increase in tire size (width). The reasoning for this is a 1 inch increase in width is 1/2 inch on each side of the wheel. So you want to reduce backspacing by at least 1/2 inch.

Backspacing can be reduced by adding wheel spacers or adapters, or of course by purchasing new wheels with the desired backspacing.

If you plan to go with 0" backspacing it will push you wheels 4.75-4.5" farther out than the already are. It won't cause any interference with your suspension or steering, but your fenders will not completely cover the entire wheels so you could get some rubbing when the suspension compresses. How much depends on the size of the tires, you lift, & how agressive your driving. You may loose some articulation going that wide without trimming the fenders. For a lifted "mall-runner," it probably wouldn't be a problem.

I'm no "expert" on the subject. Someone correct me if I'm wrong.

[IStan]

comattack

Wtf does a 0" backspacing look like?!

[Comattack]

comattack

Wtf does a 0" backspacing look like?!

I have no idea... I was speaking theoretically.
nsaladino mentioned he found some wheels with 0" backspacing.
If that's correct, I think 0" backspacing would make the mounting pad even with the inner lip. But I don't think you'll even find any wheels like that...

Maybe he means 0 offset?!? but that's a different animal altogether...

[mitchinphx]

comattack

Wtf does a 0" backspacing look like?!

go to the bario - you'll see

[IStan]

I thought he meant 0 offset at first.

What's bario?

[nsaladino]

Yeah, see that why I didnt understand why these wheels I was looking at had 0 backspacing. Thanks for the info it must be wrong information. If anyone can figure out what the backspacing on the KMC XD series Rockstars is let me know. It says 0 backspacing and 0 offset, which just simply doesnt make sense to me. Oh and what is the factory backspacing on the TRD 16" wheels? 4.75?

[Comattack]

Here's what I found on those particular wheels...

Rockstar XD Series
KMC Wheels
Available in:

18x9- +0mm offset
20x8.5- +10mm and +35mm offset
20x10- -24mm offset
20x12- -44mm offset
22x9.5- +12mm and +38mm offset
22x12- -44mm offset
24x12- -44mm offset


INFO:
• Available in chrome and matte black paint
• 20x8.5 and 22x9.5 are newly released sizes to fit non lifted light truck and SUV’s. ex: Cadillac Escalade, New Ford F150, Range Rover, etc.
was the wheel of choice by the OE project vehicle mfg’s at this years 2005 SEMA Show in Las Vegas (Ford, Lincoln, Nissan, Toyota and Dodge)


XD NOTES:
• The XD122 Enduro, XD716 and the XD756 will carry over into 2006 and will be available in chrome only
• Also, all three styles will also have the ability for customers to purchase a bolt on XD Series Ring in black or chrome like the Diesel and Balzac

I'm assuming you are talking about the 18x9 wheels...
I did find one site that has them listed at 0 backspacing, 0 offset. That is most definately a typo. I have yet to see ANY wheel that is 0 backspacing. But 0 offset sounds more reasonable.

If the offset is 0", that puts the mounting pad dead center in the middle of the wheel (equally spaced from the inside & outside). If that is the case, you just divide the total width of the wheel in half to figure out what your backspacing is and you get 4.5 inches. If your initial figures are correct (< 4.75-4.5), you should be fine. I don't have a Tundy, so I couldn't tell you for sure, but One site I visited recommended a tire size of 285/50x18 for those wheels on a Tundy. Will be different if your lifted and wanna go oversize.
Just make sure you get them from a reputable dealer and you'll be sure to get the right tire size/wheel combo. But it sounds like those just might work.

[nsaladino]

That makes sense, thanks for the info.

[sak]

comattack

Wtf does a 0" backspacing look like?!

It'll probably make the car look like a lowrider model.




Basically it would mean that the mounting point on the wheel is exactly at inside of the wheel, pushing all the excess width of the wheel outside of the vehicle. So the wheel itself tstarts at the rotor hub and outwards.

To get an idea, take the wheel off your car and match the inside of the wheel to the hub itself. That would be equal to 0 back spacing.

It would however make the offset half of the eidth of the wheel.

[DevinSixtySeven]

the less backspacing you have the greater the scrub radius becomes. eventually you will push the tire in to the back (or the front, or both) of the wheel well when you turn.

-sean

*edit* oh and if you really did mount a 0 BACKSPACED (not offset, like he said undoubtedly a typo since theres no such thing as zero backspacing AND zero offset) rim, your bearings etc. will not last long.