I put new Firestone Destination tires on My 97 Blazer 30,000 miles ago and already the outside edges on all tires are worn slick. Is this an alignment problem or something to do with shocks/suspension? Thanks.

 

This is normally a sign of mis-alignment. This web site shows some good illustrations to read tire wear.

 

Have you rotated the tires at all since you put them on 30,000 miles ago? If not then that is your problem.

If you have been rotating every 5,000 miles or so like you should then it is an alignment problem.

 

I agree that tires should be rotated ~5-6k miles, but there is still an alignment issue that needs to be addressed. Better to be aligned and not rotated than rotated and not aligned.

 

As already said, if you have not rotated your tires since you put them on, that is mostlikely the reason for the accelerated wear, but an alignment problem is also likely.

Another thing to note is that some tires do not last all that long. The factory tires on my Rainier only made it to 32k before they were toast. All four of them.