[ThompsonXTerra]

Okay guys. Noob question. I get the concept of backspacing, but how does it work? Like, I read one guy saying that he has 3.8 inch backspacing and then another saying he has 4.75 inch backspacing.
My question: What does that mean? Is 3.8 sticking out of the fender more than 4.75 or the other way around?
Thanks guys!

 

[TJTJ]

Okay guys. Noob question. I get the concept of backspacing, but how does it work? Like, I read one guy saying that he has 3.8 inch backspacing and then another saying he has 4.75 inch backspacing.
My question: What does that mean? Is 3.8 sticking out of the fender more than 4.75 or the other way around?
Thanks guys!

Backspacing (BS) is the distance from the part of the rim that bolts to the truck's hub, to the far side of the inner (Brake side) lip of the rim.

Crappy Pic:

The line where the angle iron in the pic crosses a length on the ruler in the rim's bowl, is the backspacing for that rim. (The depth of the bowl that the above ruler would be measuring)

So, if the brake-side of the rim's bowl is deeper, that means it has MORE BS.

The more BS, the more of the rim is pulled over the brakes, so, the less the rim STICKS OUT.


If the bowl is shallower, it means the rim sticks out MORE...and that there's LESS BS.



So, just remember that BS is the bowl's depth, and, the deeper the bowl, the more BS, and the tighter the rim is tucked into the well.


So, a rim with 3" of BS sticks out more than one with 4" of BS.


On 2000 - 2004 X's for example, 5.5" of BS gives the most FRONT tire clearance. This is because the front is IFS, and STEERS, and, the less BS, the wider the arc the tire swings through, hitting more stuff in the way.

On the X's REAR, it is a live axle, and less BS gives MORE tire clearance.


This is one reason why some of us use 5.5" BS in front, to be able to fit larger tires, but add rim pacers to the rear to DECREASE the BS, and increase REAR tire room.

I ran 5.5" BS rims for the 5 mounted tires on my 2001 X for example, but used 1.5" spacers on the rear hubs...to reduce the rear BS to 4".

 

[ThompsonXTerra]

Thank you TJ! This all makes a lot more sense now. So the minimum backspacing X owners can do without cutting is 4.75, correct? And is the stock rim size on 2000-2004 SE models 16 or 17 inches? I found some 16x8 inch rims with 5" backspacing, but if they won't fit the tire I have on my stock rims I'm not going to get them.

Heres the rim:
http://www.tirerack.com/wheels/Whee...el=Xterra+XE+4x2&autoYear=2002&autoModClar=V6

 

[TJTJ]

Thank you TJ! This all makes a lot more sense now. So the minimum backspacing X owners can do without cutting is 4.75, correct? And is the stock rim size on 2000-2004 SE models 16 or 17 inches? I found some 16x8 inch rims with 5" backspacing, but if they won't fit the tire I have on my stock rims I'm not going to get them.

Heres the rim:
http://www.tirerack.com/wheels/Whee...el=Xterra+XE+4x2&autoYear=2002&autoModClar=V6

The minimum BS w/o cutting depends on the tires....and if you have a BL too.

IE: If you want wee baby 28" pizza cutter tires you can use less BS and no BL and they'll still fit.

If you want big boy tires, which for 2000 - 2004 X's would be ~ 33 x 12.5, 5.5" is the minimum BS, and for every bit less than 5.5" of BS, you do MORE CUTTING.

IE: For anything over 31", you cut some front wheel well plastic, with 33x12.5's requiring the most plastic, but no metal trimming.

Here's a 2001 X with 33 x 13.5's, on stock rims, with no metal trimming:

This has 3" SL/2" BL, on stock 16x7 alloys with 5.5" BS, and no metal trimming.


If the above X had 5" of BS instead of 5.5", metal trimming would have been required.


IE: For any given amount of trimming, you can fit larger tires with 5.5" of BS than with less BS.

The more metal you want to trim, the less BS you use. Anything less than 5.5" will require trimming for full sized tires.

33's, even with 5.5" of BS, need you to either raise or remove the front fenders so they clear the tires when the tires stuff up into the wells.

So, a 2-3" BL is needed for 33's to have UPTRAVEL room, regardless of trimming or SL or BS, etc. (Throwing the fenders into the garbage does the same thing as far as room, but looks a bit more mad max than some of us like to look, etc)

 

[ThompsonXTerra]

Right now I have 31s on the stock rims (I would never go down from that). Eventually I do plan on getting 32s, would I need to trim metal if I had those with 5" backspacing?
Just trying to figure out if the rims I mentioned above are a good investment or if I should wait and get 15" rims when I get new tires. That would just be in a few years since my tires are fairly new.
Thanks again.

 

[SRStaff]

To give you a rough estimate. 31" tires on OEM 5.5" back space required no trimming at all. With the 5" back space of the wheels I have now; I barely had to trim the bottom plastic lip on the front flap.

 

[ThompsonXTerra]

To give you a rough estimate. 31" tires on OEM 5.5" back space required no trimming at all. With the 5" back space of the wheels I have now; I barely had to trim the bottom plastic lip on the front flap.

Got it! Thanks man. I've been thinking about just taking that plastic piece completely off anyways.