After trying a couple other 17" tires for my GenIII I decided to give the EP422 a try. I've always been disappointed with the fuel economy drop that comes with upsizing to 17" wheels and I hoped that using a very fuel efficient tire would reduce this hit. In all the tests I have read, the EP422 is always on top in terms of fuel economy as long as the Energy Saver A/S was not in the competition. Since the Energy Saver A/S is not available in a 17" size usable by the Prius I figured the Ecopia was the next best thing. I decided to try out a set of 205/50/17 tires because I like the taller sidewall and extra ground clearance they provide vs. the 215/45/17. They are just a tad taller than the OE 15s but the 215/45/17 is smaller than the OE 15s. The smaller tires will further increase the speedometer error and decrease ground clearance while increasing wheel well gap. All bad things IMO. The only drawback to the 205/50/17 is most of the tires are only available in an XL (Extra Load) rating so they ride worse than an SL (Standard Load) tire. The XL rating means they are stronger and more resistant to blowouts and punctures. Here is my review of them. Please keep in mind that even same model tires behave differently in different sizes. The 15" version may be different than what I experience with the 17" version! From TireRack.com Bridgestone Ecopia EP422 Tire Specs (205/50/17 93V XL) Bridgestone Ecopia EP422 (Grand Touring All-Season) UTQG=480 A A, 10/32nds, 22lbs, 829, $149 ($70 available rebate) My initial impression of the Ecopia EP422 is first how cushy the ride is and how poorly it handles compared to the Continental PureContact and the Michelin Primacy MXM4. The tire feels fairly mushy at first and steering response is slow. When pushed really hard in a fast corner the tires feel like they are folding over but traction is ok. After they broke in, straight line driving and normal turns feel fine. The car just feels somewhat cushy yet I'm not afraid to take corners faster than most people would ever want to. Don't get me wrong. I would NEVER suggest this tire to a sports car enthusiast or any of my SoCal buddies who like slinging their dropped Prii through the curves. For the majority of drivers I feel the tire is more than adequate for everyday driving needs. Noise: This tire is quieter than the Primacy MXM4 but only marginally so. Over smooth surfaces and rough surfaces the tire is pretty quiet although you can definitely tell when road surfaces change. Noise was also lower than the PureContact. Being a 17" tire the road noise is definitely higher than with my old 15" Energy Saver A/S. Handling: let's start off by saying if handling is a big priority for you then you may want to look at another tire. This tire doesn't really handle well at all. I was not impressed with the handling characteristics of this tire. The ride was comfortable and relatively quiet for a 17" XL rated tire. Compared to my 17" Primacy MXM4 (215/45/17) I feel these tires are a step down in terms of handling and general steering feel. Steering input is really subdued compared to the PureContact but those tires made even the MXM4 feel sloppy. Like i stated above, don't buy this tire if you enjoy slinging the car through fast curves. However, the tire feels safe and performs well for the average Prius driver who wants a little more out of their car but doesn't want to sacrifice too much fuel economy. This is a smooth riding tire. Traction: Traction is pretty decent despite my negative opinion of its handling characteristics. I have been able test them in everything but snow. They provide decent traction in dry and wet conditions but the soft sidewall doesn't inspire much confidence when going into a corner fast. Once set into a sharp curve the tires stick well enough. I performed a dry and wet braking test from 30mph and in both conditions the car stopped hard and fast. They are much better than any of the 15" tires I've ran! They are not the stickiest tire compared to my other 17" tires but they do well enough in most conditions. This tire rated very well for snow and ice traction compared to some other all-season tires. I know that is not saying much but the tire does not rate very higher in dry traction so I would have never guessed it had better snow traction than the ProContact with EcoPlus of even the AVID TRZ! I believe the snow traction is also better than the Energy Saver A/S so for those who need a tire with a little more snow traction yet want the fuel economy of the Energy Saver this may be a good alternative. TireRack's snow test: Tire Test Results : Eco-Focused All-Season Tires: Do They Deliver on the Promise? Eco-Focused All-Season Tires: Do They Deliver on the Promise? Mileage: this is where my review becomes worthless. I have not been able to really make any solid observations on fuel economy because of drastic weather change, change in fuel formulation, change in driving patterns, etc.. The tires roll well and judging by a few tanks where I could control a couple variables I am confident these tires will be good enough for high 50mpg tanks once summer comes. I'll update once I am presented with conditions I am familiar with. I have not had a GenIII in the winter yet. To further compound the fuel efficiency comparison is the fact that the speedometer now reads almost 100% accurate. With the OE 15" tires, the speedo reads 1mph to 1.5mph too fast. With a 215/45/17 the speedo reads almost 2mph too fast. I checked the odometer via GPS and it consistently reads about 1.69% too slow. So if the GPS says I traveled 48miles the odometer says I traveled 47.2 miles (approximate because I don't have the numbers in front of me). This really screws with FE comparisons between the three different sized tires! With my 15" tires the error between displayed and calculated mpg was between 4.8% and 5.8% on average. The two tanks I tried to calculate on these taller tires brought the error up to almost 9%! So while I may be getting better FE in real life, trying to calculate it with the odometer being off and the speedo reading correctly makes it difficult to see it. Grrr We know from TireRack.com testing that this tire is usually more fuel efficient than any other tires included in their tests. Compared to other LRR 17" tires, I estimate the EP422 to be 1-2mpg more efficient. The PureContact is likely the next most fuel efficient. See the TireRack test here: Tire Test Results : Eco-Focused All-Season Tires: Do They Deliver on the Promise? Appearance: It's a pretty average looking tire. It's not ugly nor does it look sexy and stylish like some of the Nitto or other race-inspired tires. I think it looks nicer than the Primacy MXM4 but not as nice as the PureContact. Price: The price of the EP422 is competitive and the $70 rebate offered at Costco and other retailers makes this tire very competitive with the Energy Saver A/S. while the Energy Saver offers a bit better fuel economy, the lower price of the EP422 plus the rebate tends to make the higher fuel economy of the Energy Saver a wash. I would still opt for the Energy Saver A/S if given a choice but that is only because I like big mpg numbers. The 65,000 mile warranty, low price, and great fuel economy make this a truly thrifty tire. Summary: This tire is designed for mpg and comfort. If you care more about high mpg numbers, comfort and low noise than you do slinging the car around corners then you will be happy with this tire. It is a very cost effective tire. In the 17" size I am very happy with the overall performance of the tire. I drive fast and aggressive at times. Despite my repeated negative comments on its handling, the tire performs well during those aggressive times that I only frown a little. Then I remember that 98% of the time the tire makes me smile. For the low cost/mile and overal fuel efficiency I don't mind frowning 2% of the time. When it comes to tires, we can't have everything!