EcoModder Forum LRR (low rolling resistance) tires - Green Seal report & list

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 01-01-2009, 11:43 AM #21 (permalink) 93 Metro Streamliner   Join Date: Oct 2008 Location: Oregon Posts: 180 AeroMetro - '93 Geo Metro Thanks: 1 Thanked 14 Times in 7 Posts I just check my odometer at a mile post on the highway, then check it again 30 or 40 miles later and see what the discrepancy is.
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And the Clarifying continues:

Quote:
 Originally Posted by Jim Allen Capri: Is that, "Interesting, that's the dumbest thing I've ever seen!" or "Interesting, cool way to do it!" ( : < )
Actually, my reaction was "I wouldn't have thought anyone would do it that way, even though that's a pretty good way to do it."

Quote:
 Originally Posted by Jim Allen .......... Either way, it's not my idea. It's how the programmer wanted you to find the circumference. Easy to do. I though it was cool. My other method is to measure the loaded radius with the tire inflated to the pressure I will use.
No!! The loaded radius is not the way to do this. BTW, this is called the Static Loaded Radius and it only affects ride height - which is why some find it a useful statistic to have.

Long story, but the short version is that the axle is off center both from the top and the bottom of the tire. The tire kind of hangs from the top and pushes down on the bottom.

Quote:
 Originally Posted by Jim Allen .......... If you have other methods, would love to hear about them! As to centrifugal forces, a tire engineer told me regarding one particular tire (a big, high profile, 38 inch diameter, 15 inch rim, mudder) that the tire grew in circumference by several mm at high speed (he did not define "high"). I never did get to question him further to see if this was a general phenomenon, or something found just on that tire, or others like it. That's why I asked you about it.

This is probably a bias ply tire - and yes, those types of tires will grow. You can see this phenomenon in drag racing - especially Top Fuel where the speeds are high and the tires are exposed.

But we are talking about radial tires with a belt which restricts the growth. In fact, growth of this nature is such a problem for radial tires that higher speed rated tires will have a circumferential overlay which further restricts the growth.
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Quote:
 Originally Posted by CapriRacer Actually, my reaction was "I wouldn't have thought anyone would do it that way, even though that's a pretty good way to do it."
Folks that are into bicycling (as I am) that need to calibrate bike computers will measure this way too (rather than use a tape measure around the circumference)... not that bike computers need to be all that precise, but still the same idea. I usually use chalk on the tread which then leaves a mark on the pavement for several revolutions before becoming too faded, and then measure between the marks.

 01-01-2009, 05:45 PM #24 (permalink) EcoModding Apprentice   Join Date: Sep 2008 Location: Indiana Posts: 131 Impala - '04 Chevrolet Impala base 90 day: 32.84 mpg (US) Thanks: 0 Thanked 2 Times in 2 Posts All tires are subject to the centrifugal force which can make them bulge slightly while rotating. The faster the rotation, the greater the chance of distortion/bulge. __________________
 04-11-2009, 08:43 PM #25 (permalink) Master EcoModder     Join Date: May 2008 Location: Maynard, MA Eaarth Posts: 7,882 Mica Blue - '05 Scion xA RS 2.0 Team Toyota 90 day: 42.48 mpg (US) Forest - '15 Nissan Leaf S Team Nissan 90 day: 156.46 mpg (US) Number 7 - '15 VW e-Golf SEL TEAM VW AUDI Group 90 day: 155.81 mpg (US) Thanks: 3,403 Thanked 2,901 Times in 1,819 Posts Hi, I recently got a TireRack.com catalog in the mail and they actually have a blurb on low rolling resistance, and they list three tires that are low(er) rolling resistance: Michelin "HydroEdge Green X" (UTQG Rating 800 A B) Goodyear "Assurance Fuel Max" (UTQG rating 580 A A) Bridgestone "Ecopia EP100" (UTQG rating 400 A B) Has anybody tried any of these, or have you heard anything about them? __________________ Sincerely, Neil http://neilblanchard.blogspot.com/
 04-12-2009, 02:58 AM #26 (permalink) Ernie Rogers   Join Date: Feb 2008 Location: Pleasant Grove, Utah Posts: 133 Thanks: 0 Thanked 11 Times in 5 Posts Accuracy of speedometer and odometer? Why not just check them with a GPS? If you are comparing fuel economy, best to make sure both cars are going the same speed, otherwise, what have you proved? With my car, a one mph error in speed makes a one mpg change. I apply corrections to both speed and odometer when it's important to know. If you increase tire diameter, fuel economy will usually increase, but it will SEEM to go down unless you correct for guage changes. /Ernie Rogers
 04-12-2009, 03:47 AM #27 (permalink) Pokémoderator     Join Date: Dec 2007 Location: Southern California Posts: 5,864 1999 Saturn SW2 - '99 Saturn SW2 Wagon Team Saturn 90 day: 40.49 mpg (US) Thanks: 439 Thanked 528 Times in 355 Posts Ernie - Yeah, I periodically use a GPS correction for my one-size-up-from-stock tires : http://ecomodder.com/forum/showthrea...ires-2642.html I apply the correction to my fuel log, so it's like a mini-bonus. CarloSW2 __________________ What's your EPA MPG? Go Here and find out! American Solar Energy Society
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Quote:
 Originally Posted by NeilBlanchard Hi, Has anybody tried any of these, or have you heard anything about them?
I contacted Michelin directly a few months ago, and they recommended the Hydroedge.

Another one that looks good is Nokian i3.

 07-30-2009, 10:53 PM #29 (permalink) Master EcoModder     Join Date: Aug 2008 Location: Monroe, LA Posts: 308 Exploder - '02 Ford Explorer xlt Rolla - '02 Toyota Corolla ce Team Toyota 90 day: 44.43 mpg (US) Thanks: 11 Thanked 13 Times in 12 Posts What do you think the rolling resistance is on these? __________________ "Jesus didn't bring 'Natty Lite' to the party. He brought the good stuff."
 08-01-2009, 04:20 AM #30 (permalink) 93 Metro Streamliner   Join Date: Oct 2008 Location: Oregon Posts: 180 AeroMetro - '93 Geo Metro Thanks: 1 Thanked 14 Times in 7 Posts I contacted Nokian also, and they said the i3 is good but the H is better.