I had the small tires at first, then I upgraded to the Alaskan bushwheel 29" Airsteaks along with better brakes/wheels from Grove. The Airstreaks are phenomenal on grass/river beds/pasture... But they wear very quickly on pavement. If most of your flying is from non-pavement fields, I'd endorse the tundra tires for sure.

Cheers,
Ackselle