MPG Differences on Wheel Sizes. - Mustang Evolution

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Old 09-18-2013, 02:28 PM   #1
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MPG Differences on Wheel Sizes.

So just take this as an example-

I have one car outfitted with 20", 8.5, with 255's all around.

Another car outfitted with 19", 8.5, with 255's all around.

And one more with 18", 8.5, with 255's all around.

Exact same tire for all cars and conditions, just curious which one will increase/decrease fuel efficiency. If you could explain how, that'd also be great!
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Old 09-18-2013, 02:30 PM   #2
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Going to depend on wheel weight. Generally speaking larger wheels are heavier which will decrease gas mileage.
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Old 09-18-2013, 02:49 PM   #3
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Also have to take into account how at highway speeds larger wheels will make the engine turn less rpms. So if you can find the balance between weight and size you can get better mpg.
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Old 09-18-2013, 02:57 PM   #4
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The width of the tries (255s) won't make a difference. Like on lifted trucks the mileage decrease from 33s to 37s to 44s is huge. But you don't go that tall on our cars. So 255/30 255/45 255/50 it don't make a huge difference.
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Old 09-18-2013, 05:21 PM   #5
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Quote:
Originally Posted by Soccerluvr4
Also have to take into account how at highway speeds larger wheels will make the engine turn less rpms. So if you can find the balance between weight and size you can get better mpg.
No...not really
A 275/50r15, 275/35r18, 225/30r20 are all going to rotate nearly the exact same. Within .5 mph difference at 65.

---------- Post added at 05:21 PM ---------- Previous post was at 05:16 PM ----------

For the op.
255/40r18
255/35r19
255/30r20

These tires are within .01 inches of each other.

The 20" will get worse mileage than the 19" and the 19" will get worse than the 18".

With this model I am making the assumption that the wheels are made of identical material in an identical pattern.
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Old 09-19-2013, 08:43 AM   #6
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Also the weight is gonna hurt too. 20s<stock wheels. 20s plus tires fattttttt
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Old 09-19-2013, 10:46 AM   #7
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Quote:
Originally Posted by lowflyn View Post

No...not really
A 275/50r15, 275/35r18, 225/30r20 are all going to rotate nearly the exact same. Within .5 mph difference at 65.

---------- Post added at 05:21 PM ---------- Previous post was at 05:16 PM ----------

For the op.
255/40r18
255/35r19
255/30r20

These tires are within .01 inches of each other.

The 20" will get worse mileage than the 19" and the 19" will get worse than the 18".

With this model I am making the assumption that the wheels are made of identical material in an identical pattern.
Can you explain your calculations? Do you multiply the tire width by the aspect ratio, convert that result into inches and then add it to the wheel diameter? I'm trying to figure things out before I buy new wheels.
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Old 09-19-2013, 11:47 AM   #8
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Each manufacturer is going to measure differently. But generally yes that's how it works.
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Old 09-19-2013, 12:01 PM   #9
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What re you wanting out of your wheels? Looks? Performance? What kind if set up? Street and daily? Strip?
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