The front opening is significantly larger. Look behind the front wheel. There is no way a 33" tire on a 4" lift would have that much clearance. There is about 1-2" of added clearance back there with about 1" up top. The rears are hard to see, but I'm gonna guess the added clearance is gonna be about the same. I'm running a 4.5" lift with front adjustables and pushed them way out to run 33" and I still don't have as much clearance as the bushwacker WJ does. My guess is that with the bushwacker flares, 4.5" lift, tag bumpers, and proper length bumstops I should be able to at least run a 305/70/17=33.5"-34" tire and possibly even a 315/70/17=34.5" tire, because right now I'm on 285/70/17=33" tire and don't have the flares and I don't rub anywhere.
Past-SOLD2000 TJ, 4.0, 231HD,4.5" long armed lift, 4.56's, detroits, 35" KM1's
Past-SOLD 2000 XJ auto 242 4.0 6" Full traction long arm, Dana 44's, MTR Kevlar 35's, 4.88s, Detroits
Present- 2002 WJ Overland, 242HD(going in soon) 4.5" Teraflex/JKS lift, JCR Sliders, TAG bumpers, 33" Muds, 17" JK Moabs ( Future- 2012 JK Rubicon)