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Hey guys,

I made the switch from the non-lrr tires that came on my CPO 2011 volt about 2000 miles ago. I immediately saw a large gain in EV miles during my normal daily driving, a no crap gain of 10% more range. This is without the tires even being broken in yet and at lower air pressure than I was running in the non-lrr tires. My normal daily driving is mostly 40 mph and below. On a 50 mile round trip 10 miles of it will be at 55 mph with the other 40 miles at 30 to 40 mph.

When the dominant factor in range / fuel economy becomes air resistance it is a different story. On highway trips at 70 mph sustained speeds my ICE mpg has climbed from a bit over 39 mpg to a bit over 40 mpg for the same trip, about a 2.5% gain in fuel economy. The only other change besides the tires is the weather. Running on the non-lrr tires earlier in the year driving temps were between 75 and 85 with appropriate use of climate control, the trips with the new tires were done in temps from 85 to 95 with appropriate use of climate control.

So, for people who do long drives more frequently than me... how much effect does outside air temp have on fuel economy? I know the AC is working harder now than it was back in May, but no idea how much it actually affects my MPG.

This is what sucks about not having laboratory testing of tires, I see every day that the lrr tires are better than the ones I had before... but are they even better than I think they are but the hot weather is masking the gains?

Keith
 

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LRR tires give you maybe 10% more range, and equivalently less traction.

However, I don't use the climate much, so going from 75 to 90 F probably gives me similar amount more range, as long as battery cooler doesn't need to run much.
 

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Keith - how worn were your previous tires?
Going from worn tires to new tires can make a huge difference alone.
They can, but in the opposite direction than you seem to be implying.

Newer, thicker tires have more rolling resistance than older, thinner tires. http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=177

When switching from OEM Goodyear LRR tires with 25k miles to new Michelins MXV4's (that weren't marketed as LRR, but were given an "excellent" rating for rolling resistance by Consumer Reports, its highest rating), I observed a shocking ~15% drop in range/efficiency. I drive a bit more conservatively than the average Volt owner, so my drop in efficiency is probably higher than others would've seen. But still. I was very surprised.
 

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So, for people who do long drives more frequently than me... how much effect does outside air temp have on fuel economy? I know the AC is working harder now than it was back in May, but no idea how much it actually affects my MPG.
This is a hard question that, without a lot more information, won't have an answer. Air temperatures cut both ways. On the "good" side, higher temperatures mean the air is less dense so the drag forces are reduced. On the "bad" side, you may need to use climate control more. Given that drag goes up with the square of the velocity, it likely depends on how fast you're going. The faster you're going the more a higher air temperature will increase range in comparison to a lower air temperature.

Also note that air pressure and humidity also matter. Higher altitudes and moister air reduce drag.
 

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1. Take your average power level for the drive with no AC (you can view the DIC to get an idea of how much power you're using at different legs of the trip to estimate, or use OBD to log it)
2. AC load is likely only 1-2kW, calculate percent of power used for AC, add percent to your no-AC fuel consumption
2b. But on very long drives your cabin is likely cooled early on and only maintenance cooling is needed, probably only 0.5-1kW

Ballpark I'd guess ~5% hit on fuel economy for AC on the long drive. Unless it is exceptionally hot with full sun load on the cabin at the same time.

I will be doing some summer road trips and logging some data just for fun. (because nerd)
 

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I just replaced the goodyears with Perelli P7's which are both LRR tires but I am taking about a 5 to 10 percent hit in range with the new tires. That equates to about 2 to 4 miles per charge. It is difficult to get accurate numbers. Others here say range will improve as the tires break in. Not sure how many miles that will take.
 

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Our 2014 Volt has factory original Goodyear tires. Now with over 40,000 miles, they are wearing quite nicely and looks like we will easily break 50,000, maybe 60,000 miles. All 4 tires are at max sidewall pressure, 51 PSI, and have been since new.

I noticed range has increased probably due to the tires wearing in, now with summer temps. electric range is about 45 + miles, and gas mpg on the ice, is low to mid 40's mpg. Yesterday my wife and I took a 210 miles long trip to Portland Oregon via hwy 30 from Astoria Oregon. When we returned home for the round trip we used 40 miles of electric still had about 5-6 miles left, and the remainder on the gas engine came out to 43.895 mpg, now thats with 87 octane gas, we notice no difference using premium. Overall mpg was over 54 mpg combined, as good or perhaps better than our 2010 Prius would have been with the same road conditions and climbing grades on both Highway 30 and Highway 26 during our trip. I like the factory Goodyears, but Costco does
not carry them. Will probably have to go with Michelin or Bridgestone when we need a set.
 
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