Should Michelin energy saver tires give cars a legal CO2 bonus?
The new Energy Saver tires from Michelin should be good for the environment (or, at least, better than previous tires since they should reduce the CO2 emissions of whatever car they're on by up to seven grams per kilometer, according to a Michelin representative). But, should these tires also be good for the automakers that use them?
That's the question that Michelin executive Patrick Ozoux wants the EU to answer. According to a story in Automotive News Europe, Ozoux said that, "When carmakers fit such tires as original equipment, they should get a bonus on their CO2 rating." The EU will likely be assigning a CO2 rating to new cars in the coming years.
I suppose the important consideration for the regulators is how long does the CO2 reduction last. Is it for the life of the car? Probably not, since the tires will likely be replaced at some point. Then again, I'm sure the CO2 ratings would naturally be based on the car as sold, right? In that case, it only makes sense to accurately assign a rating that includes the reduction from the low rolling resistance tires.
Related:
[Source: Wim Oude Weernink / Automotive News Europe]
Reader Comments (Page 1 of 1)
Tony Belding 10:21AM (1/24/2008)
I agree with Ozoux. It should be based on the car's performance as it comes from the factory. Somewhere down the road the owner will replace the tires of course. It's a safe bet that equally (if not more) efficient replacement tires will be available, so it would then be the owner's responsibility to shop for them.
There are a lot of things owners can do to affect the mileage (or CO2 output) they get from their cars, for good or bad. Manufacturers can't be responsible for all of those factors, they can only be responsible for the car as delivered.
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Karkus 10:28AM (1/24/2008)
It's really very simple. CO2 ratings are determined by a fuel efficiency test (same as l/100km or mpg). Whatever tires come standard on the vehicle will be used in that test. It's not like they "assign" a rating somehow and caluculate the effects of the tires.
I don't get what the question is here. If you put LRR tires on your car, the fuel efficiency test will result in a lower CO2 number lower. Period.
You can't really control and account for what owners do with their cars afterwards, how much they junk they carry around, how much they weigh, whether they keep their tires inflated, etc.
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scatter 11:25AM (1/24/2008)
I agree with Karkus. The CO2 emissions are tested on a rolling road so I would expect that the effect of the tyres would be incorporated into the results of the test. Wouldn't they?
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Steve 12:17PM (1/24/2008)
You know, you only have about 1 square foot of tire contact with the road at any given time. Do you really want to reduce the rolling resistance, which is incidentally the very thing that allows you to stop?
You may think it's a minor safety concern and that the fuel-efficiency improvements outweigh the increased stopping distance. But I think that's a crock.
The thing is, people tailgate a LOT. Ever tried driving at 60 in the right lane? I do it every day to save gas. And every day I get at least one moron who justs sits RIGHT behind me instead of passing. Thanks for trying to save me money on gas, but I'd rather he have low-efficiency tires so he can stop instead of plowing into me. (And meanwhile the people driving fast on the left all end up tailgating each other waiting for that one idiot to get out of the left lane.) I'd also rather have my own tires be capable of stopping ME when I get into trouble. Those of you who aren't especially concerned by the safety impact have clearly never been in a high-speed wreck. In the 1800s they used to think people couldn't survive 60 mph travel. They were wrong, but people definitely CAN'T survive a 60 mph impact.
People have no idea just how fast they're really traveling. It's just a number to them. But speaking as someone who knows what it feels like to be out of control at 85 mph, I can tell you: the speeds our cars reach are really beyond our comprehension. And all you have to stop you from continuing on at those speeds into stationary objects is 1 square foot of rubber. I'd rather save lives than gas.
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rgseidl 2:12PM (1/24/2008)
@ Karkus, scatter -
the dynamometer test pairs the tires with a steel drum with just 3-5 times the diameter of the wheel. The contact conditions therefore differ from the real world in terms of both material pairing and geometric curvature. Significant calibration efforts would be required to extrapolate real-world CO2 savings from the test results.
Note also that low-resistance tires tend to generate less grip than conventional designs during high-speed cornering, especially in the wet. If your driving style is careful and leisurely, that's probably not an issue. However, if you're the kind of person who is often in a hurry and/or enjoys driving fast, you may want to stick with conventional tires for safety's sake. Fuel economy is important, but it's not everything.
Of course, it still makes sense to shell out for a tire pressure monitoring system if you're not already in the habit of regularly checking. Incorrect tire inflation is a very common operator mistake that invariably accelerates tire wear and usually increases fuel consumption as well. The dynamometer test is far too short to capture the benefits of a TPMS, so it would make sense to give manufacturers a CO2 bonus IFF it is standard equipment.
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Karkus 2:55PM (1/24/2008)
LRR tires actually have just as much grip/stopping power as regular tires. (if fact, LRR may be better).
Look at this extensive study:
http://www.iea.org/textbase/work/2005/EnerEffTyre/calwell1.pdf
One study (Slide 20) shows that there is NO correlation between "Traction Composite" and rolling resistance. Another study shows that WET braking distance is actually slightly LOWER (better) for low rolling resistance tires ! (Slide 26)
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Karkus 3:47PM (1/24/2008)
Hey Bloggers !
How about doing a post to bust the myth that LRR tires aren't safe?
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kballs 9:30PM (1/24/2008)
I've said this before many times. Thanks for the link Karkus.
Rolling Resistance != Traction
RR is caused by deformation of the tire around the contact patch. Deformation does not give you traction, tread on road gives you traction.
You can lower RR by decreasing the size of the contact patch (lowering traction), but there are other ways to decrease RR while keeping the same contact patch. Some manufacturers (including Michelin) have done just this. Go look at the low-RR tire ratings and you'll see, not only is RR lower, but traction is actually HIGHER on many of them.
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Nucbuddy 1:06PM (1/25/2008)
@Steve,
"In the 1800s they used to think people couldn't survive 60 mph travel."
Strange, considering they had already been exceeding 70 mph for quite a while.
http://en.wikipedia.org/wiki/Bobsleigh
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Nucbuddy 1:13PM (1/25/2008)
@Karkus,
"You can't really control and account for what owners do with their cars afterwards, how much they junk they carry around, how much they weigh, whether they keep their tires inflated, etc."
In other words: Cars don't burn fuel. People burn fuel.
http://www.google.com/search?q=guns+don%27t+people+kill
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Nucbuddy 1:19PM (1/25/2008)
@Karkus,
Also, cars don't use gasoline if people don't drive them.
http://www.google.com/search?q=%22Cars+don%27t+use+gasoline%22
Fuel-economy regulations increase the fixed-costs of cars, while making it cheaper to drive them. Thus, fuel-economy regulations encourage people -- in more ways than one -- to drive more.
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