I realize that there is relatively little difference between a 285 and a 265 tire overall, but if a 265 was kept as a spare, could damage occur to the drivetrain (mostly differentials) if the 265 was used as the spare with 285s? Vehicle is a 2002 f-150 supercrew FX4.

Thanks for any help,
Scott

 

I think so!
If you were running in 2 wheel drive then you could use two slightly different sizes in the front but not the back. Basically, the end driving the vehicle must have the same overall diameter tires.

I originall had 265/70/17's on my truck and just recently went to BFG285/70/70's. This size spare will just barely fit but it will definitly go under the truck. I traded the old spare for a new BFG and only paid 70$ difference so to me it's work it to trade it in for the correct size. This keeps you from moving all your tires around in case you get a flat at the rear of the truck.

I'm not an expert but i think i'm telling you correctly.

 

If you have a LS in the rear, you need both rear tires to be the same overall "HEIGHT". If you have a 4x4 and the front is engaged, keep the same overall "HEIGHT" all the way around.

 

what they said