The very first improvement to the van was to get some better tires. I didn't have faith in the factory tires. We like to drive on old logging roads with sharp gravel. I've seen a lot of silly flat tires from sharp rocks on my friends rigs. I'm not interested in changing a tire in the mud when it's 36 degrees and raining out.
Here I am, investigating a rock stuck in the rotor or something. Squealed like crazy but nothing was there when I got the wheel off
I went with 5 new Cooper Discoverer AT3 in the stock size. I got the 10 ply for supreme durability.
http://us.coopertire.com/Tires/Light-Truck/DISCOVERER-A-T3.aspx
I'll rotate the spare in to give longer life and keep all 5 tires at the same wear level. That way, if one tire gets a fatal tear in the sidewalk I won't have to buy 4 new tires.
So far I really like them. They are quiet on the road and seem to be great in the dirt. I haven't seen snow with them yet.