The manual suggests agains chaining the front do to possible machine damage from rubbing. Rear should be fine. it appears that I have enough clearance.
The new John Deere Cab tractor which has a cab right from John deere and is my size tractor doensn't have clearance. They put the tank under the wheel wells under the fenders!
If you haven't checked one of those out yet, you have to. They are very nice.