what is the largest tire you can fit on a 1999 silverado with stock suspension

 

im runnin 285 75 16s now, i have run 305 70's before with torsion jacking

 

is torsion jacking what makes the front end sit level with the back. and if so how does it work

 

yeah, it just turns your tosrion bars to the max, making your front end always be maxed to its highest ride. makes for a stiff ride and isnt good for alignment

 

Would purchasing torsion keys for my truck achieve the the same ride heigth in the front as in the back? thanks

 

Yes, torsion keys are what you need. You'll spend between $60 and $100 plus an alignment and possibly sacrifice your ride quality. Maxx Cam is pretty good and adjustable.
If you want to fit bigger tires, install a body lift and you can fit 35's. On stock rims you'll rub in hard turns or turning during suspension flex, but not much.

 

would i sacrifice anything by running 285 75-16's

 

This is my second set of 285/75-16 in three years and have not had a single problem, even though Mickey Thompson recommnends at least a 2in body lift