Proper Backspacing & Offset for 2wd?

[Vaughn MacKenzie]

Can anyone tell me the proper offset for my truck? Or know a good place to go to find out? I am looking at a deal on some wheels that have 5. 25" Backspacing and 10mm Offset, does not say Positive or Negative.



Thanks

 

[Un-Hemi]

You didn't say how wide the wheels you are looking at are. Most of the aftermarket 16X8 wheels I have looked at have 4-1/2" or 4-5/8" backspacing. I don't know what 'offset' is but I'd be interested to know how they fit if you purchase them, as I prefer to keep the tires under the truck also.



Tom

 

[Vaughn MacKenzie]

They won't work

Hey Tommy, thanks for the reply.



Well I did some checking last night and Offset is the distance the mounting pad surface is from the centerline of the wheel.



Backspacing is the distance from the mounting flange on the back side to the pad surface.



I removed a wheel on my rig last night (I have the stock Aluminum wheels that came on my 2001) I measured:



Backspacing: 6. 0"

Rim Width 8. 5" (this surprised me because I always thought they were 8. 0")

Offset: 1. 75" or 44mm (positive, ie, mount pad is toward outside of wheel)



This seems quite a bit different than the aftermarket wheels I've seen. With less offset the wheels will stick out more, not good for clearing fenders and not good for steering & suspension.



The wheels I was looking at are 18x8. 5" so they are the same width as stock. But their offset is not right so I'm passing on them. They are Weld Renegades in Polish finish for only $175 but designed for Chubbys



Vaughn

 

[Mactruck]

Vaughn, I believe Rim width is measured inside the bead area, not the overall rim width. The reason is because outside rim width can vary depending on the thickness of materials used (IE. Steel, aluminum, Cast or forged)



I've been keeping my eye on the M/T Challengers. They have almost the same backspacing at 4 9/16. These might be a good fit and they are not as expensive as the Welds.



I just wish someone would come out with a 9 inch wide rim for my 295's :{ They are all either 8 inches or 10 inches wide. (except some Centerline wheels at 9 1/2 inches)

These would be a perfect fit for alot of us.

 

[Vaughn MacKenzie]

Mactruck, you are probably right about how rim width is measured.



I wonder if the offset/backspacing is the same on both 2wd and 4wd trucks? I was surprised at how far outboard the mounting pad is (positive offset) for a rear-drive vehicle. If I measured correctly, and if the 4x4 truck wheels are the same as mine, the I don't think the wheels you are looking at will cut it. They'll stick out too far.



If I do wheels they'll be 18" diameter, last I checked M/T had nothing in an 18" but I see more and more 18" & 20" wheels coming available for 3/4T trucks and tires to go with them. So I think if M/T wants to keep up with the times they would come out with 18" wheels.



Vaughn

 

[Un-Hemi]

Offset and backspacing must be related. Obviously, if you increase backspacing, the offset is going to increase also (assuming that it is positive). In the good old racing days, nobody ever heard of offset; wheels were ordered with the width (Mactruck is correct about the wheel width being measured inside the bead) and the backspacing.



The aluminum wheels on the 4x4 and 4x2 are the same. There's no distinction in the parts database.



Keep in mind that 18" load range E tires will be VERY expensive for the immediate future, until production is ramped up. 16" will be relatively inexpensive for a long time yet.



Tom