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-   -   Fuel Efficiency (http://www.focusfanatics.com/forum/showthread.php?t=310872)

clayton89 03-04-2013 09:07 PM

Fuel Efficiency
 
My friend has found a pretty good deal on a set of OZ ultraleggeras 16 x 7 and he currently has 15 inch steelies. He was curious if the increase in contact patch of the tire going from 185 - 205 will offset the increase mpg factor of having lightweight wheels of approx 5lbs lighter?

Thanks for your comments

Edit: He has a 05 4 door focus

bringler26 03-04-2013 09:28 PM

It may but most likely it would be negligible.

as an example I went from 16" wheels with 205/55/r16 tires to 17" wheels with 225/45/r17 on my Subaru and actually got better fuel economy because the wheel and tire combo was lighter than the original size.

clayton89 03-04-2013 10:54 PM

That was my thought, but I am guessing that the stock steel wheels weigh like 20 lbs plus the weight of the tires. So my guess would be that the 16 inch tires would weigh about the same maybe less, But I do believe that saving 5lbs per wheel will be very beneficial for mpgs.

bringler26 03-05-2013 12:13 AM

It depends on the tires really. My 16" tires around 25lbs each and my 17" tires are about 20lbs each. The wheel weights I do not know off hand but i had looked the weight of my tires on tirerack.

clayton89 03-05-2013 04:48 PM

just looking on tire rack at a few tires it looks that the 16 inch tires are around 20lbs versus 15 inch tires are around 18lbs

clayton89 03-05-2013 04:56 PM

OK looking at a post on the forum from Julian at Tire Rack stated that theirs are like 19lbs a piece shown here and over on this discussion it looks like the factory may weigh 20.5 lbs (figuring a 18lb tire 38.5 - 18 = 20.5) do you guys think that a total weight loss of wheel weight 5lbs plus the 2lb gain in tire and greater contact patch width would hurt gas mileage or hardly be noticeable?

wrc_fan 03-05-2013 05:03 PM

don't forget the aero impact :D

clayton89 03-05-2013 05:21 PM

I know lol. I just know I have seen a few people here complain about their mileage based on increasing wheel sizes, but usually they all increase the width of the tire. I have seen a few people say that with the increase in contact patch will increase friction with road surface leading to less MPGs

felixthecat 03-05-2013 05:44 PM

Quote:

Originally Posted by clayton89 (Post 4621462)
I know lol. I just know I have seen a few people here complain about their mileage based on increasing wheel sizes, but usually they all increase the width of the tire. I have seen a few people say that with the increase in contact patch will increase friction with road surface leading to less MPGs

Thats where friction comes in= more friction= more stick. Get mpg eco type tires & you'll loose friction but have better mpg.

Levi05 03-05-2013 06:25 PM

If you do some deep research, you will find that wider tires will typically have less rolling resistance. And going to a wider tire doesnt increase the contact patch but only changes the shape of the contact patch (if tire pressures remain the same as before).

It gets complicated but simple answer is a wider tire alone wont hurt fuel mileage. Wheel weight and tire compound/tread design have a bigger impact.

Go to autospeed.com and lookup an article called "tyres, grip, and all that..." <- explains everything. Haha.


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