To buy lrr tires or not- is that the question?

From what I have been able to deduce, the OEM tire is the lowest RR tire available for the Prius. The only thing lower that is currently available is the Bridgestone B381, but its only available in a 14" for the Civic Hybrid. Its actually about the same diameter as the Prius tires, so if you could find a nice light 14" wheel for the Prius it could be a nice upgrade. I don't know of anyone who has tried it yet though.

The other tires frequently discussed all provide a significant improvement in traction and lifetime, but are all higher in RR. Some claim they are close enough that they don't notice a mileage hit, and they're still certainly on the better end of the spectrum.

Since I live in a place with no snow, and hardly any rain, I am leaning towards just going with the OEMs again for my next set.

Rob

 

The Nokian tires mentioned a lot here ARE LLR tires. Which is why many get just as good or better mileage compared to the stock tires.

Do be aware the term LLR is only relative. They aren't -THAT- much better.

 

I replaced mine with a set of Nokian i3. My MPG remained the same (if not better) and it is the only known 15" rim tire that weights less than OEM and comes with 80k mile warranty.

 

maybe the honda civic IMA 14"are a lot lighter then the prius
mmm need to go and look for some salvage ima wheels

any specs?

 

Agreed, LRR is a very broadly applied term. From the spotty bits of data I have seen (mixed with my spotty memory), most of the LRR tires on the market currently have resistance coefficients in the .008s or 0.009s. The OEM goodyears on the Prius are in the 0.007s, and the B381s are 0.0062. The one bit of data I can find on the Nokian's is .00085 for the NRT2.

Rob

 

Consumer Reports rates the rolling resistance of the TripleTreds as "Very Good" (its second highest rating category). So I think that if the rolling resistance of the TTs are higher than the Integrity's, then it's not by much.

I wonder what's up with California's testing of the rolling resistance of 100+ tires now on the marketplace. I think the report was originally supposed to come out in 2006, but it's still not out yet. That would be really useful info to have.

 

How about some real data. The attached spreadsheet covers 130k miles and 4.5 years of driving on three different tires.

• The original Goodyear Integrity tires for 44.5k miles
• Michelin MXV4+ "Energy Saving" tires for 55k miles
• Nokian WR tires for 31k miles and still rolling

The Michelin tires improved MPG over the Goodyear Integrity tires in the winter, averaging about 0.5 MPG better for a 12 month period.

The Nokians are doing even better and I will have enough data for a definitive 12 month comparison in about 3 weeks.

JeffD

 

You're kidding, right? There is no way you could separate the tire contribution from environmentals for a differential as small as this.

 

No, not kidding. Averaging over a 12 month period (and about 30k miles) accounts for most of the environmental variables. I also did a calculation comparing the first year and second year of MXV4+ MPG and determined that the change in revs per mile accounted for almost all of the MPG difference in the data between the two years. My driving use has been very consistent over the 4.5 year period and I have been very careful in evaluating my data (I am an engineering professor). You can look at the data yourself and see the consistency in it.

JeffD

 

What we can't account for in this sort of analysis is the general trend of improving mileage over time. As the car breaks in, and the driver gets better at driving a very different type of car we find that most Prius drivers get better mileage the longer they drive their Prius. To get a little bit more conclusive data what we would really need is for someone taking this level of data to switch back to a new set of Integritys later in their cars life and see if they actually do go back to their fist year kind of results. Since most people aren't big fans of the Integrity for other reasons (tred life, traction) I don't know that we've ever really seen that data point.

Rob

 

Were you able to buy a tire?

 

Rob,

Since I don't make much of an effort to get better gas mileage (hence only 45.6 MPG), the data shown is reasonably consistent over the 4.5 years. I do admit that I will NEVER put (or accept on a new car) Goodyear Integrity tires on any car I own.

JeffD

 

Exactly correct. And, you can't control for variables such as cumulative wind speeds, improved driving technique, cumulative temperature effects etcetera. The data is SUGGESTIVE at best.

For instance, I put Michelin XRadialDTs on my Prius and saw an instantaneous drop of about 4-8% in MPG (from 54-56 MPG to 52-54 MPG per the MFD). But, there was a nearly simultaneous drop in temperature as well. I think, but cannot prove, that each event contributed about half of the MPG loss.

Also, the idea that you can drive consistently enough in conditions similar enough to ascribe 0.5 MPG (1% change at 45 MPG) is patently ridiculous.

The only way to accurately describe a tire as LRR is to measure its rolling resistance. The only way to accurately measure MPG changes due to tires or oil or anything else is to do test in controlled conditions or collect enough data about conditions to statistically control for them.

 

JD,

I am shocked, that as an engineering professor you would think that your data would be much proof of anything. The mileage in my Prius varies a couple mpg depending on the mood I am in. Not to mention, traffic conditions, number of passengers. But mainly my point is that driving style dramatically affects mileage. There is no way that anyone drives consistent enough to attribute a couple mpg difference to any specific variable.

 

The TTs aren't LRR but I didn't notice a big decrease in mileage when I started using them so they aren't bad. They are louder than the Integrity but a LOT 'grippier'. They worked well for me as snow tires the first 3 winters (not that you have to worry about that in Venice). After 50K miles, I figured the tread depth was getting low for snow and I put on Hakkapalita RSi for last winter, saving the TTs for summer. Should get one more out of them, the siping on the outside is getting thin.

 

Another big variable is the quality of fuel on mileage ,ie.,freshness ,ethanol,octane,or other additives which even from the same vendor can change.............

 

What is the definition of LRR anyway? And does anyone know how, as compared to other true snow tires, the Nokian R Snow Tires stack up? Nokian claims they are the lowest RR snow in their product line but I have no clue whether that really means anything of consequence.

 

As I understand it, a big part of the reason there is so much confusion is that there is no formal definition or agreed test standard. California has been trying to force the tire manufacturers to agree on a standard and publish test data for all tires sold, but they have met a lot of resistance getting it implemented (pun intended).

Rob