[NorCal 4x4]

The backspacing should be between 5" and 5.8", stock is 5.5" which for an 8" wide rim, has a +25mm offset.

On a 8.5" rim you would need an offset of around +18mm for 5.5" of backspacing, and on a 9" rim, about +12mm of offset will give 5.5" of backspacing. A 17x8 is wide enough for most tires, and you're more likely to rub at the pinch weld with a 9" (especially if it has the smaller backspacing like 5").

For tires, the best size for a 17" rim on a unleveled Titan is a LT285/70/17. You can find this size in most of the popular brands and models. Even Bridgestone now offers an AT Dueler Revo in this size now, where before only the P285 was available in the Revo. BFGoodrich AT KOs, and Nitto Terra Grappler ATs have a more aggressive look, as do the Toyo M/T, but I think you would need a LT265/70/17 for the Toyo M/T.

Btw, I'd be PO'd at my wife if she surprised me with rims or tires as there's no way she, (or probably most members here), would get the ones I would like. Cut him a check or a credit card. And since different places carry different brands, don't saddle him with a gift card to just one place. Just a thought