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Old 07-15-2009, 11:13 AM   #81 (permalink)
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Thanks, CapriRacer, I was hoping for an explanation from our resident Tire Geek.

I feel the tires on the Insight are larger than they need to be. They're rated for 937lbs, and the car weighs <600lbs at each corner when fully loaded.

However, I can't seem to find low RR tires for road vehicles smaller than an Insight but larger than a bicycle. Are there such tires, in the range of 150-600 lbs max load per tire?

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Old 07-16-2009, 06:53 AM   #82 (permalink)
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Quote:
Originally Posted by RobertSmalls View Post
Thanks, CapriRacer, I was hoping for an explanation from our resident Tire Geek.

I feel the tires on the Insight are larger than they need to be. They're rated for 937lbs, and the car weighs <600lbs at each corner when fully loaded.

However, I can't seem to find low RR tires for road vehicles smaller than an Insight but larger than a bicycle. Are there such tires, in the range of 150-600 lbs max load per tire?
One of the lesson from the Ford / Firestone situation a few years ago was that the way load carrying capacity is calculated for a tire needs to be refined downward - the tire needed to be larger. Put another way, there needed to be more unused (reserve) capacity.

This was partially because the average joe doesn't check his inflation pressure regularly, but also because vehicle operating speeds have been gradually been on the rise.

But for rolling resistance, larger is better.

Every tire has a tread and 2 sidewalls. The sidewalls do not consume much of the fuel when rolling. About 90% is the "tread" - the tread itself , the steel belts. and the plies. Because of this tires with larger capacity are every so slightly more efficient - same 2 sidewalls, but a larger tread.

Large capacity tires tend to weigh more - and that affects the accelleration - but in the big scheme of things, how much more fuel is consumed when accellerating larger tires, compared to the amount of fuel consumed when rolling. I tend to think that larger capacity tires would result in overall better fuel economy. But I am sure there is a point beyond which the gains are small arer not worth the effort.

Besides, tire sizing is limited by what can be stuffed under the fender.

So I don't think you should be looking for smaller tires if your goal is better fuel economy.
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Old 08-31-2009, 04:16 PM   #83 (permalink)
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I found a "new" tire from Falken.... Falken Sincera
Falken Sincera SN-828 tires listed by size

extremely high wear resistance (rated 500), low road noise, available in 13" 14" and 15"

The Discount Tire eBay store offers free shipping
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Old 09-29-2009, 01:00 PM   #84 (permalink)
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I've still been seeking and haven't found any real "data" out on 13s (very minimal on 14s)...

did find an interesting statement though (probably not news to you guys)... me want now
Quote:
Originally Posted by consumersearch.com
New fuel economy ratings coming

A new law requires tire makers to start telling consumers how fuel-efficient a tire is. As part of a sweeping energy bill signed into law in December 2007, the National Highway Traffic Safety Administration must develop a system for rating tires' fuel efficiency. Right now, the only fuel efficiency information comes from independent testing organizations, such as Consumer Reports, which test tires' rolling resistance. The NHTSA is supposed to have the new rule in place by the end of 2009, according to news reports. The law also calls for the creation of a nationwide program to educate consumers about tire maintenance, such as proper tire pressure, alignment, rotation and treadwear -- all of which can boost fuel economy, safety and durability.
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Old 09-29-2009, 01:02 PM   #85 (permalink)
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Old 09-29-2009, 01:50 PM   #86 (permalink)
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whats interesting... only the one tire, Goodyear Integrity, has sizes that even come down to 13" (let alone, not one even has the right size 14" for most older European cars: 185-60R14, 185-65R14 would be the closest)... Goodyear Integrity wet and snow traction rating is so bad its almost scary
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Old 09-29-2009, 01:54 PM   #87 (permalink)
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I know. I'm running 13s too. Best bet would be to ask basjoos. He runs through the miles (and tires) enough he can have meaningful comparisons.
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Old 09-29-2009, 04:34 PM   #88 (permalink)
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this Kumho tire looks promising... several 13 (including a 155) and 14 sizes, and has numbers much better than the Integrity
Kumho Power Star 758
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Old 09-29-2009, 04:49 PM   #89 (permalink)
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The tirerack ratings do not include Rolling Resistance. I can almost guarantee that, with those other numbers, these are High rr tires. That will give lower fuel economy.
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Old 09-29-2009, 06:25 PM   #90 (permalink)
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really? hmmm.... I thought "Low noise" was a sign of low(er) RR as it was an indication of less friction on the road surface?

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