All I've ever seen is theory on this. I'm convinced if the rolling diameter is within 1-2% from front to back, there will be no issues. Considering most DSM's out there these days are running four different tires and I'm not seeing blown VC threads every week, I'm inclined to think it's not much of an issue. I'm going staggered on my 1G this spring when I find a deal on the narrower front wheels I need. I'll report my findings of actual real world data.
