Mostly hardwood (oak and maple, some hickory some beech) I would guess but not a lot of big stuff, I would say the biggest trees are probably about 2 feet in diameter with maybe a few 3 foot trees in there.

By large, i mean a diameter of almost 5' at the base.when I purchased the house this was one of the first things that i looked to repair. 

The pilot holes for the lag bolts are typically 1/16-1/8 of an inch smaller than the diameter of the lag bolt making the mechanical base act as a sub flashing, and then there is also a chemical sealant (caulking, geo-cell, Henry's... depending on the installer) sandwiched between the roof decking/paper and the mechanical base.

Only about half of the house's roof was caught on fire and made a hole of about 3 feet diameter around to the outside of the house.

As mentioned that steel pipe builds up scale and corrodes from inside and the diameter of the inside hole will continue to shrink over time.

Pay attention to the diameter of the toilet flush valve, the bigger the better.Since you are re-doing the bath, I would not consider anything but tile.

----------------------------------------------------------------------RE: Being AudaciousWilliam Tingle (Sub2 Teacher) said, "I WEAR A 5 inch diameter Yellow button w black letters that says:I BUY HOUSES FAST!"

It certainly wasn't there a year ago, but the tenant cannot remember when they saw it first time.It has yellow borders, about 12 inches in diameter and is not soft or damp or moist (it was raining hard a few days ago).

the pilot assembly is completely enclosed, accept for a 3" diameter hole which leads to outside air.

They had a diameter of ~42" each (huge/old).In any event, I wouldn't park under a dead tree because I would not want to deal with fixing my car.