I'm running a set of 395/85R20 XZLs on my Unimog U500 camper with a heavy rear axle load: 7500-8000kg. Load rating is 8500kg at 95psi at up 70 mph per axle; 11200kg per axle at 55mph at 123 psi. I've had no XZL problems but I bought a new XML in Tucson when a rear shock broke in half and ate the inner sidewall out of the adjacent tire (not the tire's fault obviously). The XML failed at 800 miles!!! Needless to say, no more XMLs for me even though they are cheap from USA6X6. I did find two 90% tread XZLs at Dollar Tire and snagged them.
Moral of the story: XZLs seem to hold up under heavy loads (I drive at up to60 mph on highways). Maybe the Camel people weren't running enough air? My use is 85% onroad, 15% off pavement. CTIS allows you to calculate tire temperatures using a simple equation.
I think the most common error regarding tires in our rigs is underinflation due to not weighing the vehicle all loaded up for an expedition, including all fluids full. I was surprised to find I was 1400 kg over Unicat's estimate and should be running 87 psi instead of their recommended 67 psi in the rear. Fortunately, being a cautious guy I'd been running 77-78 before the weigh-in and driving 60 instead of 70.
I have run 9.00 and 11.00R16 XLs on my now defunct F350 crewcab camper (6000 lb front, 7000 lb rear) without any trouble whatsoever, just fairly rapid tire wear. The XZLs on my Unimog are wearing at a rate estimated to last 68K miles with 4/32" left.
Dollar Tire is a great place, they have lots of 9.00-11.00R16 XLs, and also 8.25R16 XZLs.
XLs are actually great in soft snow, OK in the rain, not at all good on ice, and have soft rubber in the tread. In disagreement with Dirty Harry, they ride soft because there's more air at a lower pressure between the wheel and the ground compared with what you are running now, unless you are moving at <4mph when you feel the tread blocks. By comparison with XLs, XZLs are much longer wearing, pack up with mud a bit quicker and are somewhat quieter and cooler running. Better for an expedition truck but not as good for a short range dedicated offroader.
Charlie