When looking at offset on a wheel, does a higher number mean it's closer to the inside or the outside of the car? Does adding a spacer increase or decrease the offset?

 

higher means closer to the inside. spacers lower offset

 

Maybe some help? http://kgm.tiwing.com/calcs/offsetcalc.htm

 

OK, so if I'm looking at getting a wheel with a 40mm offset, if I get a 5mm spacer, it will push the wheel out further, correct?

 

Correct, as the overall offset would be (40mm - 5mm = ) 35mm.

- Erik

 

Creeve & Bluefox280

What they said...

 

OK, with that part settled, how little offset can i get away with on stock 17" tires without rubbing?

 

Well remember, offset is in relation to the wheel width, and not the diameter.
What's the width of the wheels you want to run with the 40mm offset?

- Erik

 

Offset also affects torque steer. The less offset that you have the more torque steer. This is why fwd cars have so much offset. It also affects how much load you put on the bearings; the less offset (the more the wheel is outboard from the center of the car) the more highly loaded the bearings are and the faster they will wear out.

 

Good questions!

I'm looking at a couple different wheels, 17x7 with 38mm and 40mm offsets respectively.

 

That's only 8-10mm difference than the OEM 7" wide wheels @ 48mm offset; you'll have zero problems.

- Erik