I just put on 33 10.50's yesterday, stock rally rims on my 1990 w/ no lift. Everything clears fine, but I am sure if I ever get it flexed right it will do some modifications to the sheet metal.
And the sand question, right on the side wall they have "Baja Champion" so I would guess that they do well in the sand.
<A target="_blank" HREF=http://1990silveradok5.coloradok5.com/>http://1990silveradok5.coloradok5.com/</A>
Gone Large and Loving It.
Keith