Well the arguments aside... I have had to use a one size difference spare tire in 2 situations.

A.)I was running 215's and had a flat. Put the 225 on and it did good for about 2 months until I had the cash up to buy new tires (235's).

B.)Had a slow leaking tire with the then new 235's, one morning I got up and it was flat, had to use the 225 spare. Worked till I got the truck to the tire shop that weekend.

So In both cases where I was running one tire size too big, and one too small it will do until you get the tire replaced. But don't push your luck though, get it replaced ASAP. Nice thing about my 31's now I have a same size matching spare. <img src="/forums/images/graemlins/kewl.gif" alt="" />