Anyone have a setup of 15mm spacers in front and 20 rear?

RCZ

Umm widening the rear track refers to pushing the wheels further away from each other. When you do that, and its hard to explain, it increases understeer because the rear track now has comparatively more resistance to weight shifting and to losing traction than the narrower front. Think of it in a more extreme case where you increased the rear track by a foot. It becomes harder to rotate the rear compared to the narrower front and that causes grip to be lost in the front first...understeer. I hope people with the technical term for this phenomenon will chime in with some real physics to explain it. I know it does and how it feels, but I could use a lesson here too. **paging ChrisSlicks**

Widening the rear tires will reduce oversteer simply because of the physical grip generated by a larger contact patch.

Widening the rear track does not equal widening the rear tires at all. Do the tires on cars with wider wheels than our stock wheels stick out the side of the fenders? Nope, they usually end flush with the fender...

Widening the rear track DOES reduce oversteer AND thereby increases understeer. (Don't yell at me track guys, I know that isn't completely true, but for the sake of keeping things simple...)

Just think about it this way... understeer is when the front tires grip less than the rears. Oversteer is when the rear tires grip less than the fronts.

For example, racecars tend to run more negative camber in the front because that increases corner grip up front and thereby reduces understeer. In theory, they could also run a narrower rear track to induce oversteer, but you wouldnt want to do that because you would be sacrificing available grip.