Anyone Have LRR Tires?

<div class='quotetop'>QUOTE(FloridaWen @ Jun 14 2007, 03:28 PM) [snapback]461834[/snapback]</div>

Don't forget they fill with nitrogen!

 

Has anyone tried the Bridgestone Potenza RE960AS Pole Position or the Continental ContiProContact is Continental's Grand Touring All-Season tire?

Ruben

 

<div class='quotetop'>QUOTE(douglas001001 @ Jun 14 2007, 01:46 PM) [snapback]461838[/snapback]</div>

I prefer to use 78% Nitrogen, since it is commonly available from all air compressors by default. That is what I recommend for anyone.

 

<div class='quotetop'>QUOTE(theforce @ May 2 2007, 05:20 PM) [snapback]434367[/snapback]</div>

Thanks for the link, Force.
But... is there something I'm missing about calculating rolling resistance from these figures?

Per Ecos Consulting 2002 tests listed:
Turanza RE92 185/70R14 has a Measured RRC/4 of .01065. Pretty close, but just above Greenseal's chosen cutoff of .0105.
Integrity 185/70R14 has a Measured RRC/4 of .00968
Best tire was B381 P185/70R14 at .00615 -- matches the best reported in Greenseal's report.

The 2002 Ecos Consulting tests were used by Greenseal to create their much-cited, very helpful but rather outdated 2003 report:
http://www.greenseal.org/resources/reports...gresistance.pdf

Per 2005 manufacturer-reported data list:
Integrity P185/65R14 has a Reported RRC/4 of .01278.
Integrity P225/70R16 has an RRC/4 of .00889. This tire wieghs 25 lb (vs 15 for the P185/65R14). I don't get why it has a lower RRC/4. <_<
Comfortred P195/65R15 has .01139.
Best tires were Michelin Symmetry P225/60R16 at .00650 - a 27-lb tire, and
Michelin Tiger Paw AWP P225/60R16 at .00683 - a 25lb tire. On both these model lines, the smaller/lighter/narrower the tire gets, the higher its RRC/4.
Michelin Rugged Trail T/A P285/70R17, at .00709 is a 44lb monster that beats the RE92 by 33%? :blink:

I must be reading something wrong here, or missing some step in the formula.

 

I'm of the opinion that LRR is nigh meaningless in everyday driving conditions. It could be useful---and, more to the point, detectable---driving on smooth gym floors.

Tell me this: if one were to "gain" 1-2 MPG, under what parameters would that be measured? As long as one season (with its temp changes) compared to another? One or two tanks of gas, compared to one or two others, with the variations in how full the tank gets? Might other variables come into play, such as average speeds (compared) or road surfaces?

Having recently had the 15-mi. stretch of freeway that I use repaved, I'm reinforced in the belief that the most underrated factors in MPG, other factors being relatively equal, is the composition and condition of the road surface. I think LRR is an invention of the overactive imaginations of preening marketing types.

If it meant much, we'd hear more about it from manufacturers, including reliable test data.

 

I cannot believe, a sales person at Les Schwab (major tire dealer in Pacific Northwest) did not know anything about LRR tires. I realize there has not been any standard developed to rate a tires LRR and that it is at this time, a manufacturer's claim only, but I was very dissapointed that a sales person at a major tire store would have never heard of the concept before. Well, maybe it was his first day alone at the counter.

 

<div class='quotetop'>QUOTE(NoMoShocks @ Jul 5 2007, 08:15 AM) [snapback]473461[/snapback]</div>

After some fairly obscure research, I figured out the whole "rolling resistance coefficient" thing to my satisfaction, at least for the moment, and it got so involved I decided to post in the Technical Discussion forum:
http://priuschat.com/LRR-tires-and-RRC-4-data-t35624.html

I must admit, as abstract as the numbers actually are, I can understand why no one is rushing to study up on them, or to promote the RRC numbers as a way of selecting LRR tires.

A few basic problems with the tests:
They test with the tires overinflated (3 psi over sidewall's max-pressure rating).
They test only when already running warm, at 80 kph only, in a straight path on a drum.
No effort is made to check or describe the contact patch under these conditions.

The only way an RRC will give you any useful info is in comparing selected tires in the exact same width/aspect-ratio/wheel-diameter... even then, the weakest-tread tire will deform the most, and tend to show the best score.

That said, within an exact width/aspect-ratio/wheel-diameter, the reported numbers do seem to give a telling rank of which tires have better LRR performance.

Cheers,
Bob

 

<div class='quotetop'>QUOTE(Ruben Cisneros @ Jun 25 2007, 12:27 AM) [snapback]467479[/snapback]</div>

I've been delighted with our Continental ContiProContact tires. I have 20,000 miles on a set in size 195/65HR15 inflated to 50 / 48 psi. The rolling resistance is excellent as is the grip, quiet, and comfort (even at such high pressure).

I highly prefer them to the MXV4+ which I've owned before. They perform nearly as well as my BFG Traction T/A H tires but offer better comfort and MUCH better rolling resistance and quiet.

 

<div class='quotetop'>QUOTE(theorist @ Jul 10 2007, 07:25 PM) [snapback]476582[/snapback]</div>

After reading CR and TireRack etc, and following your advice re the ContiPro's, we just put the 185/65/15's on our 2007 Prius. They were on sale at the wholesaler, and my local tire shop (where I've bought all my tires for 15 years) installed the new Continentals for $275, minus a $100 credit for the OEM's (with 1200 miles on them), for a total cost of $175.

That is probably the best money I ever spent--they are way quieter (what noise they make is more of a white noise--higher pitched--and far easier to live with), and seem to handle and feel much better.

But the real bonus is the LRR. I did several coast downs from 30 mph to 20 mph on a nearby level residential street with the GI's the day before, and again on the way home with the new ContiPros, both sets at 40/38psi. Not totally scientific I know, but the distance increased from 1290 feet to 2030 feet!

I'll report back in a few months when I have mpg and wet handling information. Thanks for the tip--wish I'd done this on day one also.

Thanks,

Tom

 

<div class='quotetop'>QUOTE(Boulder Bum @ May 2 2007, 06:38 PM) [snapback]434302[/snapback]</div>

hello first time here.have 07 touring goes all over the place ,ie wandering car goes bye it moves over two feet ,had taken to dealer three times they did alignment allthree times said cant duplacat tech told me to get stiffer sidewall tires.these stock tires where rated "v" so i bought wider low profile 18 " icw rims looks great but still drives the same anyone else have simalur problems.

 

<div class='quotetop'>QUOTE(palary @ Aug 2 2007, 07:00 PM) [snapback]489632[/snapback]</div>

The first two weeks my Wife drove our new '07 Prius Touring she had several "strange" experiences on I-4 at 60+ MPH on windy days. It was first thought to be alignment, tire pressure issues but that was not the case. It was that the steering in the Prius was "new and very different", very sensitive, and when the crosswinds blew on I-4 she was "overcompensating" too much with this sensitive steering. We also installed a BT PLATE which helped a bit, not as if it was a full blown set of front and rear anti-sway bars, but it helped.

So now you have youself FOUR "spare tires" on rims (take-offs). Did the tire shop take 'em in on trade or ya' gonna sell them?

 

<div class='quotetop'>QUOTE(NoMoShocks @ Jul 5 2007, 10:15 AM) [snapback]473461[/snapback]</div>

A Les Schwab experienced saleperson here in Oregon also had never heard of the LRR concept.

 

<div class='quotetop'>QUOTE(qbee42 @ May 3 2007, 12:08 PM) [snapback]434451[/snapback]</div>

Michelin Energy XM1 are Michelin's lowest rolling resistance tyre, thay are standard on Australian released Prius, all models. 195 60H X 15

Sorry I don't know if they are better than the tyres fitted to US Prius but I expect they are.