would a 255/65R16 spare be good as a "donut" with all the rest of my tires 265/70R16?

 

Why? You can't really use the space savings?

 

You don't want any differences if you have AWD.

 

as mentioned there is no savings or point to a 'donut' spare on these trucks, the full size hangs underneath and doesnt affect interior space, just get a full size and be done

 

No. It would not.

 

The u-pull-its are a good place to visit for this. Many trucks have their spares intact, full tread.... like new.

 

ok...here ya go....255/65-16 means 255mm wide with a side wall height 65% of the width with a 16 inch wheel. So lets run the numbers. 1mm is .03937inch, so 255 x .03937= 10.039 this is thread width in inches. Now 10.039 x .65 = 6.526 this is the side wall height. To find how tall your tire is double the height 6.526 x 2 = 13.052 add that to the wheel diameter 16inch, and you get 29.052 total tire height. This long boring post means your spare is 10 inches wide and 29 inches tall.
The 265/70-16 is (after rounding numbers) 10.5 wide x 30.5

 

[I'm still a (very) strong advocate of implementing a 'You can not post the same day as you register.' rule. I hate drive-by posts.]

 

I get the frustration, I am on many, many forums, boat, motorcycle, truck, many car forums, miller welding, machinist, gun....lots. The thing is many people use forums for a problem they are having, it's not a social meeting for them. I too hate posts that are left hanging, I try to give results or "close" a thread if I've started one. The vast majority of people though are going to ask a question, read the answer and move on, or find the answer somewhere else and never look at the forum again. If you could not post when you joined, very few people would be here and no advertisers would buy space because they want traffic and without that, you have no forum at all.