is it ball joints?

'98 XJ. Alignment is dead on. Experiencing major outside tire wear on both front tires.

I second JohnJohn's post.

Same problems on 88.

From my experiences, ball joint problems usually cause inner tire wear. It's weird that they would cause camber in that direction to cause the outter wear. I would change the ball-joints anyway if it's been a while on large tires. It definitely would be the first thing I change.

If you get them, go to completeoffroad.com. They aren't on his page, but he can get them if you call. They are spicer brand, and cheaper than you will get "cheapies" anywhere else. _nicko_

i had some dead ball joints on my 90 that caused hella outer tire wear...

If the ball joint are bad enough to cause outer edge tire wear, the bad joints should have been discovered while doing the alignment. I'd double check your ball joints to make sure that they're all tight just in case the alignment shop was asleep at the wheel.
Jack up the front of the vehicle and support it under the axle tube about a couple of inches off the ground, then get a long pry bar to lift under the tire; up and down/in and out (in the direction of camber) not side to side. You should have zero play in all four joints.

How long do ball joints typically last on a stock XJ? I have 140k and just got new tires, about to get alignment...don't want to waste any $$. Should I replace ball joints first?