Understanding Wheel offsets & Link to all FAQ...
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FAQ's

The offset of a wheel is what locates the tire and wheel assembly in relation to the suspension. More specifically, it is the measured distance between the hub mounting surface and the center line of the rim. Below is an explanation of the various types of offsets which are pictured in the above graphic.
Positive Offset
A positive offset occurs when the hub mounting surface is on the street side (the side you see) of the center line of the rim. Most factory rims will have this type of offset.
Zero Offset
When the hub mounting surface is centered within the rim, it is known as a zero offset.
Negative Offset
If the hub mounting surface is on the brake side of the center line of the rim, it is considered a negative offset or "deep dish".
Note that extensive negative offset can potentially cause increased steering wheel kick-back and place additional stresses on the vehicle's entire suspension.
Special THANKS to Todd at Discount Tire for this info!
Last edited by Xsta Z 28; Dec 11, 2003 at 04:36 PM.
A spacer would make wheels that have too high of an offset (oe vette rears) fit without rubbing. They can also be used to push the wheels out farther for a more agressive look.
I believe H&R makes a stud/spacer combo kit that replaces the whole assembly. More expensive, yes. Safer...MUCH!
If you have a 56 mm offset wheel and used a 5/16" spacer, ( ~ 8 mm) would make the wheel fit as if it were a 48 mm wheel.
Does that clarify? Like Todd states, spacers can be dangerous, especially if the wheel studs are compromised to be too short.
HR Springs makes VERY nice hub and wheel centric spacers ( meaning the the center is designed to fit around the "button" on the axle and they create a new "button" for the wheel to center onto.)
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Bolt Pattern, 4.75" Offset, around 40mm should work just fine, although you may seriously want to consider 17" diameter, 9" width, looks killer.
Back Space, is the distance fromt the back side of the rim to the lug mounting surface.
Back Space and Offset are actually related to each other.
To measure back space one lays the rim face down on the floor, sets a long straight edge accross the back of the rim, and with a tape mease determine the distance.
Hope that helps.
Back Space, is the distance fromt the back side of the rim to the lug mounting surface.
Back Space and Offset are actually related to each other.
To measure back space one lays the rim face down on the floor, sets a long straight edge accross the back of the rim, and with a tape mease determine the distance.
backspacing = (rim width / 2) + offset
Maybe I misunderstood the explanation of backspacing but that formula seems to fit based on your explanation. Am I way off here?
Theres more info in the stickies at the top of the forum
BTW as far as I know and OEM 17" wheel from a SS or WS6 is 50mm offset and 7" back space.
All my offsets were perfect for my C5. The tires lined up perfect with the edge of the wheel well, and I have 1" clearance for the 305/35-18 Nitto DR's mounted on 18x10.5 Z06 Motorsports!
Thanks DTD!!!



