Update: I just put 35 knobbies on my Aurora. Tons of room still on the fork, and still a decent amount in the rear. however, I don't think I'll be able to fit full fenders on the back with anything larger than about 38. 35s are as large as I can ever imagine myself needing, but the LHT or Crosscheck might be a better choice for you if you want to go up to around 45.