Long shot looking for big rims for a mini t!!

[bandyleg]

Hi everyone, at my local club we run an odd balls race and i have been messing around with my mini t, im hoping some body could help me. Im looking for either a converter of some type so i can run buggy wheels or some over sized wheels that will take buggy tires. We run outdoors on a full grass track so the standard sized wheels just dont cut it.
Any help is much appreciated.