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Discussion Starter · #1 ·
Sorry if this is an overworked topic, but I couldn't find any other thread covering it.

Anyone have any real world data using low rolling resistance tires on an EV. Specifically I'm looking at the Goodyear Assurance Fuel Max tires.

I might start out by putting a set on an ICE car. It needs new tires and these are in the right price range, but I'm not expecting much of a difference.

I would expect that on an EV they'd make more of a difference. Anyone tried them?
 

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I found a list, but it's an old one:

http://en.wikipedia.org/wiki/Low-rolling_resistance_tires

I'm actually comparing them now because I'm looking to extend my range. The problem is that most manufacturers don't publish the actual rolling resistance values. This is mainly because each different SIZE tire has a different rolling resistance. So, if they make 29 different sizes of Fuel Max tires, each one would have a different RR value -- due it it's size -- even though they have the same pattern and tread compound.

- Paul
 

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Discussion Starter · #3 ·
I found a list, but it's an old one:

http://en.wikipedia.org/wiki/Low-rolling_resistance_tires

I'm actually comparing them now because I'm looking to extend my range. The problem is that most manufacturers don't publish the actual rolling resistance values. This is mainly because each different SIZE tire has a different rolling resistance. So, if they make 29 different sizes of Fuel Max tires, each one would have a different RR value -- due it it's size -- even though they have the same pattern and tread compound.

- Paul
Lots of "Lower Rolling Resistance SHOULD save you between x% and y%" no real world numbers.

You're right that there also doesn't seem to be a real metric for comparison.

There doesn't seem to be a downside to these tires, price and specs (wear, grip, etc.) are about the same as a higher rolling resistance tire, so if there's any saving/range increase it's a bonus. It'd just be nice to know - especially if one low rolling resistance tire is significantly better than another.

The Goodyear Assurance Fuel Max are supposed to be the tire choice for the Volt which attracted my attention.
 

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This isn't an EV but I recently installed a set of Yokohoma Envigors (205/65-15) on my wife's BMW 530i and they are delivering a subjective 5-10% improvement in fuel mileage as determined from the onboard MPG computer. It's hard do make a direct comparison due to varying wind conditions, but a trip between K.C. and Houston plus several 500+ mile trips to visit our son in western KS (both with the previous BFG and new Yokohoma tires) showed an improvement from 26-28mpg to 28-30mpg. The Yokohomas are 51psi vs. the 44psi for the BFGs, and I went with the lesser approved tire width (205) rather than the standard 225 width. So, I can't say for sure whether the higher pressure, narrower width or tire design were the major contributing factor; probably all contributed.

I was surprised to see such a significant improvement; especially since these tires have a softer and quieter ride than the BFG or the Goodyear tires on our van. BTW, I went to a taller profile (65 series) to maintain the same tire diameter or revs/mile so as to not affect the odometer/speedometer readings.
 

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Going from race tires to streets tires triples the range on my gasser.


On a more useful note, Blizzak tires consistently give me 10% better gas mileage than my regular street tires -- that's a result I was surprised to see from a snow tire.
That is surprising; too bad it's so hard to get good info about rolling resistance, just like it's so hard to get good info about how to take care of LiFePO4 cells. We are all beta testers doing the manufacturer's job.:mad:
 

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How about increasing your tire pressure to 10% of the maximum?

Example: Maximum on sidewall = 40. 40-4= run at 36.
 

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Paul / Farmer,

Going over the max pressure tends to distort the tires, which can make them out-of-round (depending on how still the walls are). I already tried it... it was awful. But on the other hand, most tire places only fill your tires up to about 75% (which is usually the RECOMMENDED pressure, not the MAX). I had 44 psi tires on my truck, and they were all set to 36 psi from the dealer. I called and asked them, and they told me they never go all the way to the max unless there is a reason for it.

You know what works REALLY good? Try the Summit Racing front drag radials... all the way around. They come on a 4-inch wide rim, and the rolling resistance is almost nothing... and the weight is less than 1/3rd of what my stock tires were. And here's the kicker.... they worked awesome in the snow too!

I'm not sure what the speed rating is, but if they can stop a dragster from almost 300 mph, I'm sure they can stop my little S-10 from 60mph just fine...

Bee
 

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Discussion Starter · #9 ·
How about increasing your tire pressure to 10% of the maximum?

Example: Maximum on sidewall = 40. 40-4= run at 36.
I've heard rumors that the LRR tires are intended to be run at (close to?) their rated pressures. If you do this with normal tires you may end up with uneven wear - the center wears faster. (Is that "cupping" or is that when the outside wears?)

So, if LRR tires really provide an advantage AND you can run them at a higher pressure with no downside, then that would be one more argument in favor of them.
 

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I've heard rumors that the LRR tires are intended to be run at (close to?) their rated pressures. If you do this with normal tires you may end up with uneven wear - the center wears faster. (Is that "cupping" or is that when the outside wears?)
Cupping is from out-of-balance, bad ball-joints or improper toe-in causing a scalloped edge to the tread. Here are illustrations of tire wear patterns:

http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch25/25readtirewear.html
 
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