California looking to classify tires by rolling resistance?
Low rolling resistance tires have been increasingly used to help manufacturers improve EPA efficiency ratings. While the specialty rubber used to be found mostly on hybrids, it is starting to find its way onto other vehicles as well, like gas-engined Ford Escape and Mercury Mariner SUVs.
According to Modern Tire Dealer, California is looking to capitalize on advances in the tire industry to increase fuel economy and reduce CO2 emissions with a new proposal from the California Energy Commissions (CEC). The CEC has assembled a draft proposal to rate tires based on Rolling Resistance Force (RRF) efficiency. All tires that rank within 15% of the lowest combined tire size designation and load rating will be designated a fuel efficient tire.
Under the CEC's proposal, tire manufacturers would have to test their product to the same ISO 28580 test protocol. The CEC is hoping that the tire ranking system will be easy for consumers to understand so they can make an informed decision when it comes time to purchase new shoes for their car or truck.
Not surprisingly, the Rubber Manufacturers Association (RMA) isn't exactly keen on the idea of additional oversight. According to Modern Tire Dealer, the RMA says the CEC's proposal would cost the industry up to $20 million, while forcing tire companies to hire additional workers for testing and data analysis (great, new jobs!). The RMA also points out that the National Highway Traffic Safety Administration is also working on its own tire standards system, seemingly rendering the California initiative redundant.
[Source: Modern Tire Dealer]
Reader Comments (Page 1 of 1)
Matt 6:22PM (6/14/2009)
What does load rating (the weight the tire can carry) have to do with rolling resistance? I'm not a tire engineer or anything, but I thought your car had to have a certain rating to meet manufacturer requirements. My jetta needs a load index of 91, so the bridgestone fuel max tires (89) don't work. Maybe I'm thinking about it wrong; anybody have better insight?
Reply
Phil L. 12:33AM (6/15/2009)
That's interesting.
Sadly, it could be some gamesmanship to make their numbers look better. It's likely easier to meet a LRR spec with less weight on the tire; changing the rating helps them do it.
It's not necessarily a problem for your car - as long as you stay within the tire's rating. It could mean that, with this tire, you won't be able to load as much in your car as the OEM load sticker claims you can.
Matt 12:53AM (6/15/2009)
One thing that concerned me when shopping for my last set of tires was the possability that an insurance claim could be denied if the tires were at fault and did not meet the manufacturer spec. A highly unlikely scenario, sure, but I don't want to test fate to save 1-4% on gas.
Matt 9:59AM (6/15/2009)
Woops, they were Goodyear Fuel Max. Just thought I'd correct that inaccuracy in case anybody wanted to look at the tires.
Nick 10:33PM (6/14/2009)
I hope it's happening for real, I've been looking for low rolling resistance tires, and wasn't able to get a good answer from any tire shop in SoCal.
Reply
NeilBlanchard 10:29PM (6/14/2009)
Hi Matt,
What is the "load index" -- I seemed to have missed something?
Sincerely, Neil
Reply
Phil L. 12:29AM (6/15/2009)
A tire's load index relates to its load carrying capabilities:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=35
NeilBlanchard 6:42AM (6/15/2009)
Hi,
So, for the lack of a load carrying rating of 77 pounds, the first commenter can't use the Fuel Max tires, to get a lower rolling resistance? I'd say that as long as he doesn't load the car to a gross weight of 5,116 pounds, then it would be fine...
Neil
Matt 10:19AM (6/15/2009)
It's really more about insurance coverage than anything from my point of view. I'm not sure about the truth behind this, but I was told that putting tires with a lower load index than what is rated can void a claim if the tires were at fault. I'm not a lawyer, and I'm not an insurance agent, but I don't want to be the guy that gets screwed because his tire blew out in a freak accident. Anyway, it's 77 lb difference per tire, so that's 308 lb for the car. When you factor in the 60/40 (not sure about that split, but it's not 50/50) weight distribution and consider that I do drive it at the limit on occasion, I just don't want to take unnecessary risks. I'm sure they would be fine 99% of the time, but I consider myself to be in the top 1% of unlucky people and don't want to test fate.
I searched all over for something that would say "it'll be fine" because I really wanted those tires, but everything I could find said "do not, under any circumstances, ever use a lower load index". I figure I'll let someone else take that risk and let me know how it works out. The good news is, there are plenty of cars that are rated for those tires, so hopefully they will sell like hot cakes and they'll expand the selection.
MikeW 10:32AM (6/15/2009)
Load index is the maximum load.
You can use 89 if your car calls for 91. Just have an extra psi or two.
Anyway, if load index was something that an insurance claim would be denied on, the Jetta would have two different tire sizes, [and two spare wheels] because the weight distribution is 60/40.
Don't sweat it, if you have the older jetta (with intergral rear trailing arms) just use 35/30 front/rear tire pressure.
The newer one with better rear suspension can have the same pressure front/rear.
BoneHeadOtto 11:29PM (6/14/2009)
Can we classify them by braking performance as well. I think that woudl be the inverse of the rolling resitance. Low rolling resitance tires are just plain dangerous. Just look at the seriously poor braking performance of the Fit.
Reply
Lad 12:43AM (6/15/2009)
@'Otto:
It's been my experience that hard compound tires can be dangerious in wet weather. I hope they keep the current grading system with wet traction rating. I think rolling resistance should a separate grading.
Reply
Dave 2:16PM (6/15/2009)
Wet weather braking has already been rated and printed on the sidewalls for years.
The Traction AA-A-B-C rating rates wet weather braking.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=48
Reply