I understand what scrub radius is and how it affects the handling of the car. What I dont understand is how it can be practically measured or calculated. In this thread, the 1g guys determined that the proper offset for 17x9 wheels is +27 to maintain a proper scrub radius. I do not how this offset was determined, if this carries over to a 2g, or how this changes if a different wheel width is chosen. Did they change the scrub radius from stock intentionally for a better handling car on a track? Also, given a situation where one can have either wider tires (within reason) with a less than ideal scrub radius, or skinnier tires (within reason) with an ideal scrub radius, which is preferable in road race and autocross? Please educate me.