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MPG nosedives!
01-31-2018, 09:11 PM
Post: #1
MPG nosedives!
I'm finding out that one major disadvantage to running 30 inch tires vs stock size is poor mpg. I went from 20.2 mph to 14.7 mpg. The only things that changed are the tire size and a cat back exhaust. Maybe i'm a little harder on the gas cause I like the exhaust sound but I really think its the tires. Comments?
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02-01-2018, 11:52 AM
Post: #2
RE: MPG nosedives!
You'll also have to take into account that your instruments are thrown off by the change in rotation distance. So your mpg average probably isn't accurate unless you're gps'ing your distance and doing direct math with how much gas you've used. Also, you're increased height increases the surface area of your tires that hits wind, increasing drag. I saw a similar drop when I swapped out the 245/55s for 245/85s on the Exploder. Looked boss though. Also keep an eye on your speed as that has changed as well by a couple mph.
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02-01-2018, 03:01 PM
Post: #3
RE: MPG nosedives!
Just to add on to the above, the increased tire size requires more energy to move and make the car go, thus using more gas to do so.
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02-01-2018, 09:37 PM
Post: #4
RE: MPG nosedives!
(02-01-2018 11:52 AM)FranktheVic Wrote:
 
You'll also have to take into account that your instruments are thrown off by the change in rotation distance. So your mpg average probably isn't accurate unless you're gps'ing your distance and doing direct math with how much gas you've used. Also, you're increased height increases the surface area of your tires that hits wind, increasing drag. I saw a similar drop when I swapped out the 245/55s for 245/85s on the Exploder. Looked boss though. Also keep an eye on your speed as that has changed as well by a couple mph.

The speedo is way off now. 62 indicated is 70 now. Even at sppeds as low as 35 the speedo indicates 3-4 less. Good thing I have a speedo app on my phone to check that!
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02-02-2018, 12:53 PM
Post: #5
RE: MPG nosedives!
I was going to suggest that but figured since you hadn't complained about getting a ticket you'd figured it out already. I don't remember, are they wider as well? Because that will increase your friction and expend more energy / gas to move as well.
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Frank the Vic — 2007 CVPI SAP, Dark Toreador Red, Stock
Mocha — 2014 Hyundai Tucson SE, Kona Bronze, Stock
Whitey the Beater — 1999 F-150 Lariat, 5.4 V8, Retired with 242,000 miles
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02-10-2018, 10:24 PM
Post: #6
RE: MPG nosedives!
(02-01-2018 09:37 PM)georgeent Wrote:
 
(02-01-2018 11:52 AM)FranktheVic Wrote:
 
You'll also have to take into account that your instruments are thrown off by the change in rotation distance. So your mpg average probably isn't accurate unless you're gps'ing your distance and doing direct math with how much gas you've used. Also, you're increased height increases the surface area of your tires that hits wind, increasing drag. I saw a similar drop when I swapped out the 245/55s for 245/85s on the Exploder. Looked boss though. Also keep an eye on your speed as that has changed as well by a couple mph.

The speedo is way off now. 62 indicated is 70 now. Even at sppeds as low as 35 the speedo indicates 3-4 less. Good thing I have a speedo app on my phone to check that!

You're more than 10% off, which means your odometer is off by that much.
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02-12-2018, 09:41 PM
Post: #7
RE: MPG nosedives!
(02-10-2018 10:24 PM)Leafy Wrote:
 
(02-01-2018 09:37 PM)georgeent Wrote:
 
(02-01-2018 11:52 AM)FranktheVic Wrote:
 
You'll also have to take into account that your instruments are thrown off by the change in rotation distance. So your mpg average probably isn't accurate unless you're gps'ing your distance and doing direct math with how much gas you've used. Also, you're increased height increases the surface area of your tires that hits wind, increasing drag. I saw a similar drop when I swapped out the 245/55s for 245/85s on the Exploder. Looked boss though. Also keep an eye on your speed as that has changed as well by a couple mph.

The speedo is way off now. 62 indicated is 70 now. Even at sppeds as low as 35 the speedo indicates 3-4 less. Good thing I have a speedo app on my phone to check that!

You're more than 10% off, which means your odometer is off by that much.

I didn't even think of the odo being off. Which means what? Its showing less or more miles?
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02-12-2018, 09:43 PM
Post: #8
RE: MPG nosedives!
Its showing less miles.
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