Lower Wheel Weight = FE Increase? - Fuelly Forums

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Old 03-17-2008, 02:59 PM   #1
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Talking Lower Wheel Weight = FE Increase?

So here is my first post. I'm just getting into the Hypermiling gig and have a quick question. It should be an easy one for the FE guru's here. I currently own a 01 Mitsubishi Mirage with an automatic transmission. I currently get 35mpg.

The tires I am running on are already descent as far as rolling resistance goes (Sumitomo HTR 200). I was thinking about getting lighter wheels to increase my FE . There is obviosly fuel to be saved by lowering the total wheel weight....but how much?

My current steel wheels weigh in at a porky 20lbs each! I was thinking of getting some aftermarket aluminum rims that weigh 12.8lbs each.

With a savings of about 7lbs per wheel...would I notice much of a FE improvement? Are we talking like a 2mpg increase? Or would it be more like 0.2? I was wondering if anyone has first had experience with this.

If the fuel savings are that minimal, it might not be worth it for me to justify the $500 purchase.

Thanks in advance!
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Old 03-17-2008, 03:06 PM   #2
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If you could find some "good condition" used replacement wheels it might be worth it. I would think that $500.00 could be spent better for a better return...or just spent on fuel.

Since you have an automatic...you could invest in a beefier Torque Converter that locks up a bit earlier and holds rpm slippage to a minimum...that might be better than just lighter wheels...Good Luck
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Old 03-17-2008, 03:12 PM   #3
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Go to www.tirerack.com. i saw some close-out wheels for $65 each in my size(185 65 14).

BTW, do you like your tires? i was thinking of buying those exact tires for myself.
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Old 03-17-2008, 03:19 PM   #4
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Thanks for the replies! The tires are pretty good. They hold the road pretty good in wet/dry conditions above 45 degrees or so. As for FE, I can't compare them to anything with this car...I put the tires on right after I bought it.

Thanks for mentioning tirerack! I didn't even think of them. They have the wheels I was interested in for $69 each. However with shipping, mounting, and balancing it still comes to $400.

Just for the sake of argument, what kind of FE increase would 7lbs a wheel get you?
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Old 03-17-2008, 04:49 PM   #5
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Quote:
Originally Posted by Mightymouse13 View Post
Thanks for the replies! The tires are pretty good. They hold the road pretty good in wet/dry conditions above 45 degrees or so. As for FE, I can't compare them to anything with this car...I put the tires on right after I bought it.

Thanks for mentioning tirerack! I didn't even think of them. They have the wheels I was interested in for $69 each. However with shipping, mounting, and balancing it still comes to $400.

Just for the sake of argument, what kind of FE increase would 7lbs a wheel get you?
okay, just a suggestion...

wait until the next time you need tires, then order the wheels and tires from tirerack and mount them yourself! hopefully they'll still have a low priced wheel for you.
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Old 03-17-2008, 06:17 PM   #6
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7lbs per wheel - you may not even notice any fuel savings - how much does the vehicle weigh? The rotational mass will not amount to much either - again 20lbs per wheel compared to 2000+ lbs for the vehicle. You will have better tire traction on bumpy roads since you have less weight bouncing around but that is about it.
The Boron treatment can't last forever if the metal wears with time but it does sound interesting.
Synlube on the otherhand uses 2-3 micron size particles of graphite, teflon and moly that I have in my motor and tranny for 16337 miles and have not changed it yet and will not have to in a long time - now that translates to big savings for all teh oil and filters I will not have to by and as for mileage try 20 miles from the gas station tonight at 51.8mpg.
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Old 03-17-2008, 09:51 PM   #7
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IMO, they would probably help mpg in heavy stop-start city traffic, though it would probably be lost in the noise in the general unpredictability of the traffic, unless you just had a long stretch of stop signs every block or two, with minimal other traffic to have to wait for, then it might show up as 0.5 to 1mpg different in a car that gets good city mileage.

On the highway, the difference will be in the aerodynamics not the weight. It seems like hubcovers off vs on is worth 1-2mpg on Marvin for example.

IMO if the wheels are upsized without widening the tire, as well as losing weight, you might see a gain from less rolling resistance. A lower profile has a bit less sidewall flex to waste energy in deforming. However, you'll see people running 13 inch 75 profile tires, that's just to get the skinnier tires I think. If the tire takes high pressure well then it might work out. If it doesn't it will roll like a tank track. Got a Tempo in the family with some 75 profile tires on that are like that, 40 PSI in the damn things and they still look a bit flat, and the damn thing is harder to push than Marvin, which has nearly 1000lb and another inch of tire width on it. They are great for the winter though, and apart from the low speed steering effort don't feel too stodgy for handling, odd that.

I've also got a suspicion that tires with a solid center rib will do slightly better for mpg.
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Old 03-18-2008, 11:51 AM   #8
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heavier the wheel, it will cosat better as it has "built up" torque. lighter wheels will allow it to accelerate easier thus using less gas but less coasting torque.

soo id say if you do alot of city driving then lighter wheels

alot of highway then maybe just leave it as is.
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Old 03-18-2008, 03:18 PM   #9
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This is a question I've been thinking about myself. A heavier wheel will require more energy to accelerate. . . but also extend coast distance. You're essentially "storing" energy in the wheel when you're moving. If you brake hard to stop, you lose it all. . .but if like most of us you gently coast to a stop (EOC) that extra energy would allow more distance traveled with no fuel burned. Maybe I need to run some calculations. . .
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Old 03-18-2008, 03:51 PM   #10
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