you really can't put bigger wheel's on their landing gear wires there is not enough room BUT maybe if you soldered washer's on the inside instead of a wheel collar that might give alittle more space I had mine out last year and was going to put dural aluminum landing gear on it but I just never got around to it. I emailed WM they sent me inst. on how to use a heat gun to straighten the wing[] I have not bought one of their planes in a while I enjoyed mine for a while but the landing gear did not just bend it would collapse on landing but I never broke out the mounting plate or split the vertical block's for the landing gear.
I had their 25 size combat spitfire I put Hayes racing wheel's on that plane they were really just 1/8 x 2 3/4 in. plastic disks I NEVER had a problem with long grass at the field. Greg