Existing stock tires on a wider rim, any Fuel Efficiency cons? - Toyota Yaris Forums

hondaconvert · 08-22-2012, 10:14 PM

Im looking to buy a lighter wheel for my 2012 Yaris, it comes stock with 15" steel rims that are 5.5" in width and Bridgestone Turanzas (P175/65R15 84H) on them. I'm looking at the Konig Zero 15" aluminum rim Z156T04385 that is 6.5" in width. Can I use the Bridgestones on the Konigs even though the rims are 1" wider? If the tire fits on the rim and works properly, are there any FE disadvantages to the wider rim and same tire?

Any info appreciated, thanks

Kaotic Lazagna · 08-22-2012, 11:45 PM

I don't see any problems with that, it's a big enough profile that it shouldn't even stretch. I don't think you'll see any disadvantages since they will be lighter rims. You'll probably actually pick up a few more mpg's.

TLyttle · 08-22-2012, 11:49 PM

Gee, we used to play this game decades ago, not for FE, but for steering accuracy. It changes the sidewall angle, and for that purpose, it worked fine. More air pressure was needed in order to keep the sidewall aligned with the tread.

This all sounds like rubbish nowadays, but it worked then...

10 Francis · 09-06-2012, 12:47 AM

I understand you can't get the Konigs in 5.5 inch width, correct?
It would be more beneficial in theory to have the narrower wheels, as they would be lighter (by the weight of approximately 10 or 11 cubic inches of aluminum alloy, fudging and estimating the measurements). Will you notice the difference in real life? No; it's minute (even though the theoretical 'effective' weight would be greater than the actual weight- rotational unsprung mass has a greater effect on vehicle performance and efficiency than static sprung weight). Also, the narrower wheels would be more aerodynamic. While the wider wheels might offer a lower coefficient of drag, they also present more frontal area to the wind, for a probable net increase in drag.
On the other hand, considering the last post, your tires may last longer at the higher tire pressures that are desirable for fuel economy, and your steering feel/ response may improve, even if there is no increase in maximum mechanical grip.
All that being said, the weight savings of the aluminum wheel over the steel wheel will probably make more of a difference than all that stuff I just wrote, and we're splitting hairs talking about the fuel economy difference between a 5.5 inch- and 6.5 inch-wide wheel with the same size tire mounted on them.

Basically, if that's the narrowest size offered for that wheel, and you like the style of the wheel, I'd say go for it.

08-22-2012, 10:14 PM	#1
hondaconvert I've made a post! Drives: 2012 Yaris L 3 door liftback Join Date: Jun 2012 Location: Connecticut Posts: 1	Existing stock tires on a wider rim, any Fuel Efficiency cons? Im looking to buy a lighter wheel for my 2012 Yaris, it comes stock with 15" steel rims that are 5.5" in width and Bridgestone Turanzas (P175/65R15 84H) on them. I'm looking at the Konig Zero 15" aluminum rim Z156T04385 that is 6.5" in width. Can I use the Bridgestones on the Konigs even though the rims are 1" wider? If the tire fits on the rim and works properly, are there any FE disadvantages to the wider rim and same tire? Any info appreciated, thanks

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08-22-2012, 11:45 PM	#2
Kaotic Lazagna View User's Garage Drives: '14 GT86, '08 Vitz Join Date: Dec 2006 Location: Central Valley, CA Posts: 9,873	I don't see any problems with that, it's a big enough profile that it shouldn't even stretch. I don't think you'll see any disadvantages since they will be lighter rims. You'll probably actually pick up a few more mpg's.

08-22-2012, 11:49 PM	#3
TLyttle Drives: 07 Yaris sedan Join Date: Jun 2007 Location: Keremeos BC Posts: 986	Gee, we used to play this game decades ago, not for FE, but for steering accuracy. It changes the sidewall angle, and for that purpose, it worked fine. More air pressure was needed in order to keep the sidewall aligned with the tread. This all sounds like rubbish nowadays, but it worked then...

09-06-2012, 12:47 AM	#4
10 Francis Drives: 2010 Yaris S HB Join Date: Nov 2011 Location: Texas Posts: 33	I understand you can't get the Konigs in 5.5 inch width, correct? It would be more beneficial in theory to have the narrower wheels, as they would be lighter (by the weight of approximately 10 or 11 cubic inches of aluminum alloy, fudging and estimating the measurements). Will you notice the difference in real life? No; it's minute (even though the theoretical 'effective' weight would be greater than the actual weight- rotational unsprung mass has a greater effect on vehicle performance and efficiency than static sprung weight). Also, the narrower wheels would be more aerodynamic. While the wider wheels might offer a lower coefficient of drag, they also present more frontal area to the wind, for a probable net increase in drag. On the other hand, considering the last post, your tires may last longer at the higher tire pressures that are desirable for fuel economy, and your steering feel/ response may improve, even if there is no increase in maximum mechanical grip. All that being said, the weight savings of the aluminum wheel over the steel wheel will probably make more of a difference than all that stuff I just wrote, and we're splitting hairs talking about the fuel economy difference between a 5.5 inch- and 6.5 inch-wide wheel with the same size tire mounted on them. Basically, if that's the narrowest size offered for that wheel, and you like the style of the wheel, I'd say go for it.