First 4 wheel from Marble CO to Crystal and back.
 

I was doing a little 4 wheeling this weekend from Marble CO to Crystal CO and back. I was going to go to Crested Butte, but a tour guide was talking to me, and suggested that my tires were not the best for that kind of trip. He suggested light truck tires. I have Big O 'Big Foot' tires on it now, with about 4/32 tread. I am getting some used aluminium wheels and going to put new tires on them. What are your feelings on this? Thanks for any input.

No, 1/8 inch tread isn't much of a security blanket between you and any road hazard-anywhere. If you buy the same size tire, save the best old one for a spare.
My wheel preferance runs to steel. If I have a severe "oopsie" out in the boonies, I can hammer on a steel wheel enough to limp home. Aluminimum isn't that forgiving.
Tires with a LT rating have heavier sidewalls, a greater weight capacity, and (hopefully) better puncture resistance. They also have a stiffer ride, you get more feedback from your driving surface.
Tread design is another set of trade-offs. The features of a great trail tire don't perform well on pavement. You have to cope with things like noise, vibration, poor tracking, tread squirm, and side slip.
I had a set of Mickey Thompson Baja-somethings. I scared the wee outta myself learning how badly they handled wet pavement!
I replaced them with a set of Yokohama Geolander A/Ts-M&S rated. Since I drive this truck to work, don't play in the mud, and like to go where most people can't, they suit me fine.

I also have been eyeing those Yokohama tires. I was also considering the Michelins, but have read very mixed reviews on these, and they are pricey. I also like the steel (I think) but I have the stock Ford steel on now, and 3 of the 5 are bent out of true, as much as 1/4 inch. I'll do some off road stuff, but not the extreme. Probably won't do a lift kit, just keep it relatively stock. Any opinions/suggestions are appreciated.