Tire Decision and Speedo Calibration

[Zilverado]

Okay, so I think I've made a decision about new tires for the truck...

I will likely be buying a new set of BFG All-Terrain T/A tires for our Pathfinder. The current set is only 4 years old and they still have a fair amount of tread left (I have not measured it yet). The plan is to recycle the "used" tires onto the 8" wide rally wheels on the truck - since it is not a daily driver, I anticipate the BFG's will still last me a number of years.

The BFG's are 31x10.5 R15

So the questions are...

* I assume the truck wheel wells should accomodate the slightly larger diameter tire? The truck actually has the heavy-half (camper special) suspension system, so it has slightly higher ground clearance than the standard C-10.

* Since the overall diameter of the BFG's is slightly larger than the P265/75 R15 currently on the truck, my speedo/odo will be slightly out. Should I look at changing the gear head on the tranny end? If so, what size would I be looking for?

Any help/comments would be appreciated.

Thanks Guys (and Gals).