How good are the standard (factory) tires?

[H3 Hummer]

I understand tires from a sports car view point and how they can dramatically increase the cars abilities but new to off-roading and Hummers not sure about Off-Road tires.
I have the adventure series tires on my H3 and they seem just fine to me. A Ranger told me they were crap and to get some new ones around 10,000 miles. Like I said, I don't know the difference but have heard that factory tires can be cheap sometimes.
Are the factory tires good tires?
Any recommendations for new ones? I don't care about smooth ride and noise, I like traction for both on and off-roading.
Another thing, I will be taking the H3 snowboarding and here in Washington state we can put screws in our tires. Can you give me any pro's/con's to those types of tires?

Thanks,