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Discussion: Choosing tires > Hybrids and Tires, Please Explain.
9 of 14

However, if they are still coming with Goodyear Integrity tires, note that these tires are not well liked for their wet performance.  Tire Rack's test of several rolling resistance tire models on Priuses matches that.  Fortunately, different tires would cost a lot less than the level 5 if that is an issue.

The 2010+ models are coming with a variety of tires today.  They've got the following as OE tire models:

  • Bridgestone Ecopia EP20 (195/65R15)
  • Bridgestone Turanza EL400-02 (215/45R17)
  • Michelin Pilot HX MXM4 (215/45R17)
  • Yokohama Avid S33D (195/65R15)

The Bridgestone Ecopia EP100 was tested in the Tire Rack test, and did pretty favorably, but as it's a different tire model, the performance of the EP20 may vary.  Interestingly, if you examine the tread pattern of the Ecopia EP20 and the Insignia SE200, they're near identical.  The Insignia SE200 is already an OE-type tire, likely with a fairly low rolling resistance, and it may be that the Ecopia EP20 is simply a re-engineered SE200 with a different tread compound.

The on-paper data of the EP20 isn't inspiring.  It only comes with 8/32" of tread new, and only rates a 380BB in the UTQG label.  It's also on the expensive side for tires in this size, at $85 from Tire Rack.  The apparently very similar Insignia SE200 (with the same UTQG rating) is only $62.  We'll see how these tires perform in the field as more of the 2010 Pri' are fielded and owners report their experience with this tire (and others that come as OE on this car).

10 of 14
Whoa!  Sorry about that.  Will refrain from that in the future.
11 of 14
Are you positive that the 15 inch steel wheels are lighter than the 17 inch alloys?
12 of 14
I'm not positive on the weight of the 15" wheels, but am positive that they're not steel wheels: they are real alloy wheels, just like the 17" ones.  They use a plastic cover over the wheel to aid in aerodynamics (just as the 2nd gen Prius 15" alloys did), but the wheel is a full alloy wheel.  The weight of the 2nd gen Prius 15" alloy wheel is right at 14 pounds.  I'd expect the 3rd gen 15" alloys to be very similar.
13 of 14
One other thing I can tell you here, in terms of choosing between the 15" and 17" tires, is to look at some of the things tire manufacturers do to get (very) low rolling resistance.

As an example, I will use two 'T'-rated Cooper tires, the CS4 and the new GFE (which I guess stands for 'Great Fuel Economy').  To help achieve better mileage, one trick is to have a little less rubber in contact with the road.  So in a 195/65R15 size, the CS4 has a tread width of 6.18".  The GFE's is only 5.85" - about 1/3 of an inch less.

Because working against that, the trend for the last good number of years (on all cars) has been to both bigger wheels and lower-profile tires on them.  Note that the 17" size on the Prius has a '45-series' tire on it.  Numbers like that used to be reserved for specialty applications and stock cars.  And to say the least, these bigger numbers will not get better mileage than a 65, 70 or even 75 series tire.

So with the trend working against great fuel economy, other things had to be done.  That is why very few of the GFE-type tires have tested out very well in CR tests up until now.  Which is what makes the Michelin Primacy MXV4 that much better of a breakthrough.

So do expect a bit of a mileage hit on 17" tires and wheels.  And expect even more if you want to choose a replacement tire that excels in areas other than fuel economy.

Again, thanx for writing.
14 of 14

And a second thing about tire width (or third, or fourth) is that the aerodynamic signature of a wider tire is, well, wider.  As the car moves through the air the width of the tires is as much of an obstacle to oncoming air as anything else, like mirrors, wipers, etc.  With a wider tire to move air around, more drag is created.

Very little about wider and/or lower profile tires equates to better fuel economy.  Quite the opposite generally.  And with a quality tire, the difference in "safety" (like handling, braking) is going to be extremely small.

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