Continental Eco Tires......
 

Continental introduces fuel-saving, all-season ProContact with EcoPlus technology - Washington Times

Well, it's just a smart thing to do......

mcrews -

Yeah, I like these. They're on my short list for my next set of tires.

CarloSW2

Too bad they don't come in 13's :(

honestabe -

Yeah, that is a shame. They only come in 15/16/17/18 wheel sizes. Here is a comparison of my current ContiProContact tire (on the left) to the ProContact EcoPlus version :

http://www.tirerack.com/images/tires...tact_ci1_l.jpg http://www.tirerack.com/images/tires...opls_ci1_l.jpg

It looks like the same tread pattern but with wider gaps. It's funny. *IF* (big if) these pictures are the same scale, the grooves on the EcoPlus are narrower. Therefore, that would imply to me that the total contact patch is the same. Do you know what I mean?

CarloSW2

Hello -

I went and looked closer. The ContiProContact line of tires has slightly different tire patterns as a function of size. Here are my ContiProContancts when new as compared to the ProContact EcoPlus tires :

http://ecomodder.com/forum/member-cf...procontact.jpg http://www.tirerack.com/images/tires...opls_ci1_l.jpg

What you can see is that I only have two "middle treads [ribs]", probably as a function of tire size. Tirerack is showing a photo of a larger size tire of that brand of tire.

I would make the claim that my old "standard-issue" ContiProContact treads are already pretty close to the EcoPlus treads.

CarloSW2

cfg83,

As you found out, unless you compare the same EXACT size, you'll have problems drawing conclusions about the tread pattern. It is fairly common for small widths to come in 4 rib patterns where wider width tires will have 5 rib - and I've even seen 6 ribs used for extremely wide tires.

Second, OE tires will break up the pattern within a tire line. The vehicle manufacturer may demand a particular "look", and that may result in more groove width (or less!), more sipes per inch (or less!), and the pattern would be adjusted according - and slightly different than the "standard" for the rest of the line. - and, of course, each vehicle manufacturer would have different specs and desires, so the resulting patterns would only resemble one another.

- BUT -

The most important thing in rolling resistance is the tread compound. The tread pattern hardly has an effect on RR at all (except for the amount of rubber used). Simply changing the tread compound can have a profound effect - up to 60%. I can easily imagine that these tires just benefitted from an evolutionary development in rubber chemistry as have many of the other recent new offerings from other tire manufacturers.

BTW, Rolling Resistance is traded off with Treadwear and Traction (especially wet traction) within tread compounds. Tires with great RR will have poor treadwear or traction. The trick is to select a tire that has a good compromise that fits your needs.

...exactly! it's how much silica (sand) or other magic-mojo stuff (orange peels?) they mix with the rubber.

http://www.instablogsimages.com/imag...e_xTuQa_69.jpg

Uh ..... Mmmmmmm ...... not exactly.

Silica just changes the proportions a bit. Needless to say, tires with good RR have more silica, but silica also negatively affects treadwear and traction, which can be compensated for!

...I believe the OP was about LRR, not treadwear and traction.

CapriRacer -

Thanks for the info on comparing treads. I think of it as reading "tea leaves" in some sense, but the visual is all we have to work with, so I am looking for "general rules" in terms of what I see.

This is almost a win-win for me. I could get a new set of tires with essentially the same tread design, so the "road feel" should(?) be pretty close. At the same time, I am driving tires with "new Eco chemistry".

I do wish they came in 51 PSI, but I can easily live with 44 PSI.

CarloSW2

...that's interesting because the Goodyear "eco" tire weighs less, yet has the higher sidewall pressure:

205/55R16 Eagle RS-A: 21 lbs, 44 PSI
205/55R16 Assurance Fuel Max: 18 lbs, 51 PSI

...wish they'd publish some standardized (SAE!) LRR numbers for the tires.

I hope you realize that most of the weight in a tire is in the amount of tread rubber. To see their LRR tire with less weight makes perfect sense.

And that the pressure written on the sidewall is somewhat nebulous as this may or may not be a function of the strength of a tire.

There is a rule in process by NHTSA to add rolling resistance to the UTQG rating - along with the removal of the "Temperature" rating, as the Temperature rating was more or less analogous to speed rating.

The rule was supposed to finalized in February of 2010, but because there was some serious - and justified - objections, it is currently in limbo.

The rule as proposed was to publish the 3 ratings (RR, Treadwear, Traction) in a label to be applied to the tire (and removed from the sidewall). Treadwear and traction tests would remain unchanged.

They successfully resolved the issues concerning the RR test (by mandating a particular SAE test - there were several!). The problem was that different tests resulted in different numbers - and while the test sorted out tires effectively, unless everyone used the same test and the same test facility, the numbers published would be different.

But they got hung up on how to express that number. NHTSA was in favor of reporting the number as a "force" - meaning that larger tires (by load carrying capacity) would look worse that smaller tires. However, if the number was reported as a coefficient (the RR force result divided by the test load), smaller tires (by load carrying capacity) look worse.

Many folks, (the tire manufacturers, vehicle manufacturers, and others) wanted to have the number reported as a coefficient (RRC), arguing that this has more meaning consumers when it comes to buying tires. (the load on a tire is the same for a given vehicle regardless of the tire size applied to that vehicle.), while NHTSA wanted to publish the number as a force value (RRF), arguing that larger vehicles would look less efficient (which they already do in the regular EPA fuel economy test) and that would encourage folks not to buy large, fuel inefficient vehicles.

The counter arguement - and the one that seemed to hit hardest - was that reporting RRF would tend to encourage consumers to buy smaller load carrying capacity tires - which is the wrong direction for safety!

The GAO forced NHTSA to reconsider the rule - and that is where it stands.

One of the problems created by the rule - which was basically unresolvable - was the EVERY tire would need to be tested. That meant that a tire manufacturer had to run a tire 3 times for every size and model so they could be sure they were getting an accurate reading. Since tire lines have many, many different sizes - and there are many, many different models - this testing would take up to 3 years to complete - and that assumes no other testing takes place - meaning no testing of new tread compounds or new constructions. Needless to say, this was unacceptable.

But the issue of test facilities getting the same (or similar) results has been resolved by mandating testing comparisons to a "standard" tire. It's called the SRTT - Standard Reference Test Tire - and it is currently used for treadwear and traction testing. The SRTT would be assigned a value and all other tires would be referenced off of that - and that means the SRTT would need to be tested regularly to track the machine drift (the drag of the bearings of a testing machine change over time, but that can be compensated for if you can figure out what it is.) This, of course, would further delay the actual testing.

I assume that many tire manufacturers are conducting tests while the rule is in limbo. If I were doing the testing, I would test the smallest and the largest tires (by load carrying capacity) and a few in between for every model they make, then interpolate the results for those tire sizes not yet tested, with the idea that they could "correct" the results as they go forward. Even that would take some time.

And that pretty much sums it up!

...being a certified "number-cruncher" I personally want to see the Crr "number" -- if you'll pardon the pun -- for where the "...rubber hits the road!"

...according to the 2002 NRC report, my current Goodyear Eagle RS-A 205/55R/16's are 0.0092, which is decent, but not in LRR country.

So what's the deal with these things?
Are they designed to run at a higher pressure?
How much do they cost?

I'm wondering how they compare to Walmart specials.

I am a big fan of Aqua-treads. They do a very good job all-around.

...they'll "roll" further before stopping because they have lower hystersis (power eating) than other tires.

...cost depends upon which brand you're talking about and then how good a "deal" you can wrangle from your local dealer (or, from Tire-Shop if by 'net).

CapriRacer -- there's an interesting chart on page 6 of this article about ISO 28580

http://www.energy.ca.gov/transportat...Dan Guiney.pdf

Testing New High Performance All-Season Tires

Looks like tire rack is starting to look at comparative rolling resistance to measure affects of tires on fuel economy. Scroll down to the bottom of the results. I've been looking at getting the Yoko ENVigor when my Avids wear out.

Yup, there's an 18% difference between the 2 tests, but only a 0.3% error between the tests.

This points to the need to compare RR values using the same test.

So, how long would it be before the new rules could take effect and we'd see rolling resistance data for every tire available to the consumer?

Also, what's the state of rolling resistance reporting in Europe?

...it's actually worse than that; the "...Range of all tires used for this example: ISO = 1.13*SAE to 1.22*SAE" ...the 18% value (1.1787(x)-number) was just the mean value, however the correlation coefficient of R-squared = 0.9972 is very good.

...but, your summary is 100% correct. Do we compare small apples or BIG apples to those SMALL- and big-oranges?!?!

I kind of figured that much. I'm just not clear about how they achieve the lower rolling resistance. Is it by compound and/or tread design, or is it simply by way of being made to run at a higher pressure?

Do you know if anyone here has tried them out and collected data on FE and rolling resistance changes?

Basically RR is caused by the amount of deflection, the amount of rubber being deflected, and the internal friction of the rubber (hysteresis).

So when a tire manufacturer wants to reduce the RR, he will take rubber out of the tire and / or change the rubber to one with a lower hysteresis. Both of these things negatively affect treadwear and traction (especially wet traction)