Full-size 22s

For the 22's(with 265/35/22=29.3"o.d.) the depth of the notch from the bottom of your frame rail to the bottom of the notch should be around 7&1/2 inches if I remember correctly from the last chevy I did. Your stock inner fenders will need to be raised or replaced with trailer fenders. Your gas tank xmember will need a notch and you can section the area above your tank to raise it some (3/4" I've done). Keep in mind that this is just a rough idea, your truck can have some differences. Just use common sense.

If you need to notch the cab just cut out the amount you need and use 16 gauge sheetmetal bent to fit, weld in, seam seal and finish off

What I did on a buddy of mine is notch the gas tank crossmember and also re-drill the front gas tank strap 1inch. But I think some fullsizes have rivets instead of bolts, but this truck had bolts.