I had heard this too, and after some investigation found out that this
was true for older design radials, but generally is no longer the case
for tires made today - except for those with directional tread.
(I remember when my family got their first Michelin radials in the late
1970's they handed out a pamphlet that specifically said not to
cross-rotate the tires.)
As always, a call to your tire manufacturer will get you the correct
answer for your specific tire.

Todd
'88 Westy

On 9/13/2010 9:31 PM, Alan Felder wrote:
> I have been told that for at least some tires, radials, that they should
> never be changed to the opposite rotation, as would be neccessary if you
> were to rotate the spare thru.  This appears to be true with the brand new
> tires on my sedan, as told to me by the manager at the tire shop.  something
> about delamination if you reversed the rotation after the tire has "set".  I
> suppose you could rotate the spare on one side only, but you would not be
> getting the full life out of the spare and the other side would still wear
> 1/3rd quicker.  I would like to do this on my westy but have not, because of
> this advice.
>
> flame on..
>
> --
> Alan Felder
> Austin TX
> 82 Diesel Westy
>