I've passed 25,000 miles on my TCH's Bridgestone Turanza EL400 tires. They all are wearing evenly and measure 7/32. My driving is about 80/20 mix of highway and city driving. I've been running the tires at 42/40 psi on the front/rear. I tend to drive the limit to 5 under and keep up with the slower traffic, when the freeway is moving. Most days I spend about 1/3 of my freeway drive in slow moving rush hour traffic.

Most likely I've got another 25K before I'll be replacing these tires. Maybe by then California will have published it's rolling resistance tire study results.

If anyone has replaced their tires and are getting as good or better mileage than the stock tires, chime in and let us know about it.