I just bought a 99 F150 about a month ago it has 235/70/15s on it, the sticker on the door says it should have 255/70/15s.
When I was putting on my reciever hitch I noticed that the spare was a 255/70/15, does this mean the truck had 255s on it from the factory?????

 

Mine had BFG Long Trail (or something like that...) 235/70/16 when I bought it used. It had the same exact spare tire, that was brand new. My sticker says 255/70/16 as well. (I even have the "Off Road" sticker, but I don't have the package.....)

So I'm not sure what really came with these rigs from the factory. I noticed an F250 LD that had 245/70/16's on it (load range D).

I put on some 255/70/16's, but just wasn't happy with the size. They still looked small for a 4x4. So traded them for 265/75/16's. Much better for my taste, but did have to adjust the speedo gear to compensate for the taller tire.

 

The base tire with no upgrades on these trucks is a 235 70 R16. There are many different upgrades availible from the factory, the 255 70 R16 being one of them. Since thats what is on the spare tire and listed on the door, that in all likely hood is the stock size. Someone went cheaper on you when replacing tires!

 

Thanks for the replies.

I guess one way to find out is to check the speedo with the mile markers on the turnpike.