Max's and I30's came from the factory with a 20mm offset on the rear wheels vs. the front wheels. Was there an engineering reason for this or just cost effective? Will pushing the rear wheels out with spacers offer any greater handling characteristics or is this solely for aesthetic reasons?

 

It's better described as a front vs. rear track difference... I think it partly involves the lateral movement of the beam with rear suspension travel, and I think it's common practice on most cars with a solid axle. This is just speculation though, so don't quote me on that; I just seem to remember Mustangs etc have the same property.

 

typically the rear wheels are in further to clear the wheel wells on stock springs when you have your three buddies in the back seat who are offensive linemen and a trunk full of beer cases.

basically, it's to allow clearance for the rear to sag excessively with a heavy load (or trailer) without rubbing the fenders.

Even my Cherokee has a narrower track in the rear than in the front....

 

A wider front track also helps counteract understeer. If you are lowered or running more negative camber, increasing the rear track width would bring you a little closer to the factory handling balance.

 

...Solid axle...