Maybe advice about not switching sides is outdated
Pitbull, your idea about using the spare in the next new set of tires makes sense, but not for me. I don't drive too many miles and it would be too long (years) before I'd need a new set. The chances that the *exact* tire would still be available concern me, plus I don't want to combine brand new rubber with years-old stuff. There were reports about problems with old rubber during the post Firestone-Explorer era, and even some proposals about date-coding tires for expiration (last sale dates, anyway).
Now I don't know if these are actual problems, or just speculation. The same may go for the prohibition against swapping rotational direction on radial tires. I'm aware of the situation with unidirectional tires (and studded snows) but that's not what I'm talking about. For a long time after radial tires became popular there were strong recommendations against switching the rotational direction of these tires. The reason was reportedly that the belts (unlike bias ply tires) would take a "set" and rotating them the other direction could eventually cause tread or belt separation.
I may well be wrong, but I think the recommended 5-tire rotation pattern in the Toyota manual doesn't include switching sides. I'll have to check it tonight, unless someone here has their manual handy.
I'm searched around and lots of folks (including the Bridgestone website) indicate that side-to-side rotation is now ok, including use of the spare in the pattern. See the Bridgestone site at
http://www.tiresafety.com/service/serv_nav.htm
So I guess I'll check my manual and do the 5-tire cross rotation if that's allowed. That seems like the best bet for my situation, where I'd rather wear all these tires out at the same time.
Thanks for the suggestions and enlightenment, guys.