you can roll the lip with a broom handle. put it between the tire and the fender lip and gently roll the tire so it pulls the broom handle up into the fender lip. obviously the rear end has to be jacked up and the trans or transfer case in neutral. Might have to start with a smaller diameter dowel rod or something and work up to the broom handle size. once you get the clearance of just pulling the broom handle through with the tire and it is no longer causing interference then you can put a bit of downward pressure on the broom handle and roll it through again and again until you achieve the clearance you want between the fender lip and the tire.
thats how us old guys did it before we had a fancy schmancy special tool to roll fender lips. did it on all sorts of muscle cars to put wider tires under the rear!!