It seems like everybody is marketing a “low-rolling resistance” (LRR) tire nowadays. Fuel-efficiency becoming more and more important, and cutting down the rolling resistance of tires is one of the easiest ways to increase efficiency.
But how can you tell if one tire is more fuel-efficient than another? Frankly, tire companies are not really helping with that. This tire is 17% more fuel-efficient than it's predecessor. This one is 10% more efficient than an unnamed competitor. This one is 20% more efficient than standard tires. Do you see the problem here? There is no real way to make any kind of fact or number-based comparison between these tires.
Granted, this is not entirely the tire companies' fault. The process of trying to make real comparisons of rolling resistance between tires makes my head hurt. The best indicator of rolling resistance in a tire is called the Rolling Resistance Coefficient (RRC). The problem here is that RRC is entirely dependent on the size of the tire and the load it's carrying, so there is no way to make a general comparison of RRC between different brands of tires, only between two different tires of the same size carrying the same weight.
That doesn't even get into the issue of how the various tires handle, an important issue given that early LRR tires gave up an enormous amount of grip and ride quality due to their very hard rubber compounds. Newer tires have benefited from technological breakthroughs in rubber compounding that allow LRR tires to be much more flexible and grippy than the earlier versions.
That's where I come in. My summer project involves conducting medium-term tests of various LRR all-season tires by driving them on my Prius for 2-3 weeks at a time to get direct head-to-head comparisons, both for fuel-efficiency and general handling. First up, Bridgestone's Ecopia EP422 vs. Nokian's eNTYRE. Both are summer-biased all-season tires.
Car: 2004 Toyota Prius “Nerdmobile”
Tire Size: 195/65/15
Bridgestone's Ecopias have an extremely soft ride, with an almost balloon-like feel to them, while Nokian's eNTYREs have a much harder, more sharp-edged feel. Which is better turns out to be a highly subjective thing. I like the feel of the eNTYREs a bit better, while my wife just adores the Ecopias.
Although Nokian is regarded as a pioneer in the field, the eNTYRE is a bit older than the Ecopias, and it shows. Bridgestone's tires have around a 2 mpg advantage over the Nokians.
The soft ride quality of the Ecopias gives them a grip that feels very sticky in dry conditions and definitely hugs the road even under hard maneuvering. The eNTYRES have a harder compound that not only feels less sticky, but will slip if pushed hard.
In the rain, the Ecopia also edges out the eNTYRE with a more surefooted feel and slightly better grip in standing water.
The soft feel of the Ecopias does tend to make them feel a bit mushy in terms of handling and sidewall response, while the harder compound of the eNTYREs gives them a very precise and responsive feel.
For the most part, both tires are priced within a few dollars of each other, but the Ecopia's greater fuel-efficiency makes it a better value overall.
Overall Winner: Ecopia
Yes, in our first Low Rolling Resistance Showdown, Bridgestone's Ecopia EP422 All Season tires have come out on top. The Ecopia's advantages in terms of fuel-efficiency and grip over the slightly older eNTYREs seems to be a testament to how fast tire technology has been changing and improving over the past few years.
Next up in our Showdown – a long-term test of Yokohama's Avid Ascend!