your not losing enough clearance to need larger diameter tires besides you will find out you can't easily get different tires for the mt2... it is one of the only mt with 2.2 rims.... I am working on an adapter to fit t-maxx tires on larger hexes and poor judgement has a thread with an exle change which looks good.. I run mine in grass all the time and no problems with clearance... If you are really going to run in the grass exclusively, change to a larger engine... .18 to .21... you will kill the nt-16 eventually.... If you want a larger head, Cen racing makes a Purple Head which is much taller for more cooling.... Hope this helps