I need to get some new rubber for my wife's car and I'm looking for some 225/40/18's that will have some decent treadlife. Performance isn't the top priority, so I've been looking for a tire that isn't ZR rated. Also, how much can you really tell by the treadwear rating? If the rating is 400, what would you guess the tire could last in mixed driving not pushed too hard? Thanks for any input you can offer!

Brian B