Tires for the K10, stock quad shock suspension

My 1984 K10 6.2 needs new tires.
This is probably been discussed, but I couldn't find the thread on it... so thought I would ask here...

I picked up some 16" rims and have the stock 15" rims. I'm currently running 31x10.5x15 on it, and was wondering...

1) What is the "equivalent" size of 16" to match the 31x10.5x15 ?

2) What is the "largest" size (both diameter and width) that will fit on a STOCK quad suspension truck before they start rubbing hard parts while turning or hitting the wheel well when the shocks compress?

Thanks for any information!

1) The closest tire size to your 31" would be 245/75R16. Very common truck tire size

2) I'm not sure on the 4WD, but on my 2WD '81 model, I had 265/75R16's with no issue. I currently have 285/75R16's (approx. 33") on my 95 Tahoe with no issues, but that's a totally different animal.

Casey