Lightweight wheels and MPG - science?

"BJ" (benjamin-bignell) 04/19/2014 at 14:35 • Filed to: Lightweight, science, these are 8 lbs lighter than stock

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I've been thinking about lightweight wheels and the benefits that reduced unsprung weight can bring for the overall handling of the vehicle. But what about emm-pee-gees?

I'm planning on doing a bit of research on the topic (in other words, google searches) but figured I would put a call out to you, Oppo, in case any of you have already studied or read about the possible benefits. Let me know what you know!

Update 1: Tire rack did a comparison test with OEM wheels, +1 lightweight wheels, and +1 "fashion" wheels. Makes for interesting reading: !!!error: Indecipherable SUB-paragraph formatting!!!

Update 2: Here's an interesting discussion on the topic of wheels, tires, tire size, and some math! !!!error: Indecipherable SUB-paragraph formatting!!!

Update 3: I found an interesting article about aerodynamic wheels on the SAE website, focusing specifically on a particular system. No discussion about weight, but interesting nonetheless. !!!error: Indecipherable SUB-paragraph formatting!!!

YSI-what can brown do for you > BJ 04/19/2014 at 14:36

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Make sure you use the same tire cause that is probably going to cause a greater change than shedding a few pounds!

CPT Speedbump > BJ 04/19/2014 at 14:39

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I'm curious as to how it'll effect my car here soon, but to lazy to test. In my cars case, its gonna have lighter wheels, but also much wider wheels and tires, so no idea, lol

Tekamul > BJ 04/19/2014 at 14:40

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reduced roatating mass will help the mpgs, but you'll only see the effect in the city, if at all. The difference will be very small. It will also help 0-60 times as well.

Louros > BJ 04/19/2014 at 14:40

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I get noticeably better gas mileage with 16" OZ Ultraleggeras and summer tires compared to the boat anchor 17" OEM Mini wheels and run flats

BJ > YSI-what can brown do for you 04/19/2014 at 14:43

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The tire size and weight have a lot to do with it as well, obviously. The blue wheel I posted weighs 8 lbs. less than the stock alloys on my Passat, in the OEM size and fitment. Thats's a significant difference, with the same rubber.

What I'm curious about is whether the mileage of a car would be affected positively, negatively, or not at all. If I do get new wheels, I won't go larger because I don't want to pay the extra for the bigger tires and the stock 17" size looks pretty well balanced already.

YSI-what can brown do for you > BJ 04/19/2014 at 14:46

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If it is lighter it will most likely cause gas mileage to go up, the engine doesn't have to work as hard to turn the wheels. Larger diameter wheels are harder to turn so gas mileage goes up even though they cause the car to have a higher top speed.

BJ > Louros 04/19/2014 at 14:54

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I'm guessing that switching out the run flats on the same wheels would make a difference as well. Do you keep detailed fuel logs? Data would be appreciated!

BJ > Tekamul 04/19/2014 at 14:55

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Good point - once the wheels are up to speed, the difference in the the amount of energy required to keep them turning is probably negligible.

Louros > BJ 04/19/2014 at 14:58

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Runflats 21 lbs

OEM wheel 23 lbs

Total 44 lbs

Summer tire 19 lbs

OZ wheel 14.5 lbs

Total 33.5 lbs

I don't keep detailed logs but I easily average at least 1 more mpg with the lighter setup

BJ > Louros 04/19/2014 at 15:04

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11 lbs. on each corner? It must feel really great when you put on those summer tires!

Louros > BJ 04/19/2014 at 15:18

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It certainly does. I would have switched to them by now if the potholes around me weren't so damn bad

tromoly > BJ 04/19/2014 at 15:39

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That's when drag is more mission-critical.

wiffleballtony > BJ 04/19/2014 at 16:50

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I didn't notice a difference on my car. But I swapped less weight for a larger contact patch and more friction.

Ferrero1911 > BJ 04/19/2014 at 18:46

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I have the Alleggerita's in your picture. They are way light. I don't really know about gas mileage and all that, because I put them on my car the day I got it, but I can tell you that they dent easily. Just a small pothole it all it takes. Both of my front wheels have small dents from not really major bumps.

BJ > Ferrero1911 04/20/2014 at 06:32

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You mean that the lip is bent/dented? Good to know - our roads are terrible on a good day... But 8 lbs less per corner - it's tempting.

Ferrero1911 > BJ 04/20/2014 at 13:16

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Yeah, the lip. At least I hope that's all it is. They still hold air fine though.