Low Rolling Resistance Tires / Low Steering Resistance Tires

A few days ago I replaced my factory Bridgestone Turanza EL400's with Bridgestone Ecopia EP422's. (195/55R16 "Touring 2007"). I can't tell yet if there's any MPG advantage, but I have already experienced one particular benefit. The new tires have what I'll call a lower "steering resistance."

From the first test drive of my Prius, 4 years ago, one of the very few things I've been less than thrilled about is the lack of power assist in the steering. To be clear, I prefer sensitive steering, meaning that I prefer when I can turn the steering wheel with very little effort. I understand that many people deride sensitive steering as "vague" and lacking in "road feel," and they argue they cannot as safely control their cars in tight situations without a lot of resistance in the steering wheel. Without entering that debate, I am simply pleased that with the new tires, the steering on my Prius feels less "sluggish" and more "sensitive." (Honda steering may be more sluggish, and Toyota steering more sensitive, but I've only driven a rather few models of each.)

Anyway, after paying for the new tires, without expecting any difference in steering, I turned out of the parking spot, and immediately noticed that steering was easier. At first, wondered if there might be some new tire oil, but after a few days of driving, the increased sensitivity persists.

Otherwise, the EP422's are very quiet -- I think a bit quieter than the old EL400's and seem to handle well. The tire store inflated the EP422's to a perfect 35/33, and at that pressure, they felt just about the same as the EL400's at 38/36. I've since increased the new tires to the 38/36 I generally use, and I must say at that pressure there is now a little more harshness to the ride than before. I'm not sure where I'll leave the pressure. I always figured if I forget to check the tires for some long span of time, by starting high, the wear pattern should be averaged by combining the time over-inflated with the time under-inflated. Recently I've been reading that, on modern tires, over-inflating doesn't cause the centers to wear faster than the edges, as on older tires, so especially if I notice an MPG advantage, I'll probably leave the pressure at least a bit high. One other curious thing: compared to the old tires, the new ones have even more of that "radial tire" "going flat" bulging at the bottom look, than did the old ones. I'd have expected low rolling tires to have stiffer sidewalls and have less of that look.

Finally, just from pressing my fingernail into the tread, the compound seems soft. Although this should be good for traction, I didn't expect that in a LRR tire.