2000 F150 XLT 4X4 - I got a flat on drivers side rear tire yesterday. I bought the truck month ago and when I got the spare down, I saw it was a different size. The spare is 265/70/16. The 4 tires on the truck are 235/70/16. Can I put the larger spare in the front and drive it until the end of the week? I won't engage the 4x4. And the rear is non-posi. Thanks.

 

If the rear does not have limited slip, you can put the tire anywhere.
Front is best though, since mismatched sized rears could make the rear end heat up a little more since there is size difference, but unless your driving 200+ miles at a time, I would not worry about it.

 

ABS on some trucks will see different speed at different tires and could give faults.
Since the rear axle only has one ABS sensor, you should be OK........... that might not be the case if the large tire was in the front.

 

Is the tire size for sure 235/70/16, 235/75/16 is a much more common size and the 265/70/16's are often swapped both ways because they're the same height but different widths.
If you're on a short trip to the tire repair shop it really doesn't matter where you put the different size tire but on a long trip or towing heavy it's generally better to put it in the front. Having two different sizes of tires in the back will cause the spider gears in the differential to be constantly spinning, if you have A limited slip differential the different size tire should always go to the front for any trip of significant distance.

 

Yes, 235/70 is the size of the tires I bought it with. Should they be 235/75?

I only needed to drive the truck today. I'll be getting a new tire in Friday along with a matching size spare. So, it'll sit til then. From what I was told by a mechanic, running with 1 odd size tire would be fine temporarily as long as its not a posi rear, and as long as I don't engage 4wd.

 

Your mechanic is correct but just to be particular if you really need 4wd to get out of someplace you'll be fine but make sure it disengages before you hit the road again.

Sorry but pretty much disregard anything I said on tire size, I was thinking of 235/85/16 vs 265/75/16 which are more common on older Super Duties, they are the both same height and not likely the tires you are looking at. The original tire size for the truck should be on the door sticker on the driver side.