I'm runnin 285/75/16's on my first gen with 3.54 gears. I had stock size ties on before these and I didn't notice any loss of power at all. I would say that with a 33" or equivalent you shouldn't have to re gear.
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04.0 HO QC 4x4 LB auto transgo VB, stock, for now
Sold 91 now intercooled W250, 388HP 923TQ on #2 only 436HP 968TQ on meth
Work Truck, 93 W350 LE Dually 5Spd almost stock