I have 33x12.5's on the stock rims...
The width is ok, you don't need skinnier.
If you add the bumpstop extensions you can keep the tires from hitting the tops of the wells, and yes, that limits the up travel.
I did a 2" BL, and it took care of that problem completely.
I also have a 3" SL, but, as you can imagine, a SL does NOTHING to change where the tire goes up to on compression (up travel)...so, I had to do the BL too.
The trimming I did for a previous set of 275/70/16's was plenty for the 33's (Didn't have to trim more)
The 2" BL is a few hours work, and doesn't require the radiator, A/C or other items to be relocated like the 3" does...it also frees up room under the truck for OBA, bigger spare, etc.
It also means I didn't need to extend the bumpstops...the wells were now further away by themselves.
I'd just do the 2" BL, its all you need to preserve articulation. It was about $150, 10 pucks w/new bolts/nuts etc...and the relocation stuff I didn't need (They put the 3" BL stuff in the 2" BL kit for some reason)
Me and a few freinds knocked it out in about 3 hours of wrenching....we did do pizza/beverages and it was raining.
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- TJ
2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....
Friends don't let friends drive stock.
http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif