[Beav]

John, if you can't see any wear why worry? The price incurred to dismount and mount four tires, plus balance probably isn't a good value. Remember that as tires wear the shorter tread is of harder compound and rides appropriately (noisier also.) Personally I start looking for new tires at the half-way mark as I hate the crappy ride of worn tires.

Other considerations: asymmetric tires mount one way to the outside, causing normal rotation to become reversed. That could be a potential issue with the tire's belt/rubber adhesion. Same with tread load changes incurred by swapping tires used to carrying weight to inside or out. Ask any alignment tech (not the schmucks behind the counter that only know what they read) what method results in the fewest potential problems and they'll tell you 'front to rear.'

I'll be putting on new shoes in the next few weeks. I'm leaning towards the Kumho ASX. I don't trust Yokos over 10k miles, the P-Zero Neros look good but the Kumhos are $100/set less and my experience with Kumho is that they are 'round' and stay round.