1/4" wheel spacer

[RCCDrew]

I just installed a 66 B Body rear and Dr. Diff relocation kit. My wheels are now too close to the leaf springs. If I use a 1/4" spacer behind the wheel will I need longer wheel studs? I am running alloy wheels. 

[brads70]

General rule with steel threads is 1.5 times the diameter engagement, I like 2x ( 1/2 thread = 1" engagement) .
 I'd suggest a quality spacer NOT cast aluminum! 

[burdar]

How close is the tire to the spring?  What is a safe minimum distance?  Most of the tire flex should be below the spring shouldn't it?  I guess it depends on wheel width, tire size, section width and aspect ratio.  A higher aspect ratio will flex more.

[RCCDrew]

It works right now. It's about 1/4" from the spring. I want to put wider tires on though and that will put the tire into the spring. Right now I am running a 275 40 17.  I believe I can run a 295 or 305 with the new setup.

[crash340]

what is the rim width and back space?

[RCCDrew]

[dodj]

I added a 6mm spacer to the rear and am not willing to run them with the stock studs. I don't feel there is enough thread engagement. I have American Racing Torque thrust wheels. I'm installing 3" studs cut down to fit. 

[RCCDrew]

Thanks for the input.