[alexiskai]

I have no personal experience with this, but I just googled "dually tires touching" and apparently it's still a topic of discussion on modern trucks. Many folks are of the opinion that contact between the tires will cause severe heat buildup, leading to premature degradation of the tires and possibly a blow-out. The recommended solutions tend to be either increase the tire pressure, so they don't flatten out as much, or install wider spacers on the lugs to physically separate the two rims. However, the spacers can't be so wide that the lug nuts don't get a safe amount of thread to grip.

I dunno if this applies to AAs, but if you're running radials then probably the situation is similar to modern trucks.