I'm not saying 30's are too small; not at all. You're getting into basically changing the gearing when you start messing with very different sized diameters. Therefore the 60-series on my street-only turbo Raider (higher numerical overall ratio). Taller tires drag that numerical equivalent down, ground clearance at the expense of torque multiplication. It's all trade-offs, and 30's basically keep you stock. You'll be fine as long as you don't follow others into the big rocks.

John B.

'87 Raider 2.6 Turbo Auto, Under Construction
'95 Montero SR, 35x12.5/15 BFG M/T KM-2's, Rock sliders, Qtr panel chop, gas tank lift, 2" BL, Aisins, 5.29s
'95 Pajero Mini
'98 Montero Winter Ed.
'04 Cadillac XLR
'03 Kawasaki ZRX1200R
'60 Ford Falcon 4Dr