I'd like to change out the normal tires on my Xenon IV with tundra tires. I currently have Aero Classic 4.00 x 6 tires on it. I've purchased the longer hubs and wider front fork/axle, but am not having any luck figuring out what size of tires, etc., that would be considered "tundra."

Any thoughts? 6.00 x 6, 8 ply? I've heard that an 8 ply might be too stiff.

I appreciate your contributions,