Forgive my naivete'... is a wheel offset some sort of spacer that has to be mounted between the wheel and the hub? Sort of similar to a centering ring?
I'm looking at all the aftermarket wheels and notice that many require an offset of some millimeter dimension.

TIA

 

Offset is used to determine how far IN or OUT the wheel will be in your wheel wells. Certain wheels need a minimum offset so that they don't rub on the suspension components or inner wheel liner. Same goes for some wheels that rub on the fender trim.

It is NOT a spacer, although spacers do affect offset, but that's not what you asked lol.

Hope this helps.

 

offset is a spec on a wheel just like the width and diameter are specs.

stock offset for many MINI wheels is around +48mm for the 7" wide rims.
that means if you were to put a line down the middle of our 7" wheel and then put 48mm outwards that is where the hub will meet the mounting point of the wheel.

 

This might help you...

http://www.tirerack.com/wheels/tech/...jsp?techid=101

 

or this one...

http://www.1010tires.com/WheelOffsetCalculator.asp

 

If you go to tirerack.com and enter your year and model of MINI, it automatically finds which wheels will fit given stock suspension.

You will notice a range of offsets that will work within a given size wheel diameter often about +37mm to +45mm.

Numbers that are less positive will allow the wheel and tire to sit further outward from the wheel well while numbers that are more positive like +45mm will be more inside the wheel well.

Negative offsets are not for the MINI. You can use spacers to make the wheel offset less. A wheel with +45 offset with 5mm thick spacer will change the positive of the wheel so that it fits like it had +40mm offset.

Offset is also written with an "et" in front of it. so "et 45" is the same as +45mm.

 

"Numbers that are less positive will allow the wheel and tire to sit further outward from the wheel well while numbers that are more positive like +45mm will be more inside the wheel well."

This makes perfect sense. Thanks to all for your responses!