I've been wheeling 39.5's for 3 seasons now (going on my 4th). It has been worth the $$$ to have the bigger tires. My front axle has 5.29's, Aussie locker, ARP knuckle and hub studs, Longfield 30 splines, Longfield Chromo hub gears, and soon to have 5th studs. My main issue has been keeping the knuckle studs tight. Hydro assist and 39.5" are tough on the Toyota knuckles.