After putting on after market rims and tires my gas mileage went from 28 to 20? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

VeganGirl · 11-21-2016, 03:38 PM

Is this normal? Immediately after installing wider rims and tires(I'm going forced induction some time next weekish) I noticed my average kept dropping and dropping slowly over a few weeks. It was at a consistent 27-28, now it's 19-20 and will not go above 21. Is that normal?

Tcoat · 11-21-2016, 03:42 PM

Yes.
Wait 'till you get FI on there!

86Boyz · 11-21-2016, 04:00 PM

Quote:

Originally Posted by VeganGirl

Is this normal? Immediately after installing wider rims and tires(I'm going forced induction some time next weekish) I noticed my average kept dropping and dropping slowly over a few weeks. It was at a consistent 27-28, now it's 19-20 and will not go above 21. Is that normal?

What kinda whims did you get? Similar to this?

go_a_way1 · 11-21-2016, 04:01 PM

Quote:

Originally Posted by Tcoat

Yes.
Wait 'till you get FI on there!

OMG THIS SO MUCH!!!!

Fuel economy sucks total balls with the turbo now. 12L/100km highway is good for me now its

lol. Its fun but cost too much in gas now

jasonojordan · 11-21-2016, 04:13 PM

Well there are alot of things to consider here.

1. Whats the Size of the new wheels (Rims as you call them)
2. How much does the new wheels weight.
3. How wide are the new wheels.
4.How wide are the new tires?

Thats the short version of the list of why did my gas mileage go in the shitter.

Kaotic Lazagna · 11-21-2016, 04:35 PM

In addition to wheel weight and tire weight, you have to factor if the new tires have a higher traction rating than the tires they replaced. More traction means more grip, which means drop in fuel economy.

One other consideration is the gas. Your area may have switched over to winter blend, which will give a drop in mpg.

I have the same mpg as the OEM wheels and tires when I have my 17x9 TC105N with 245/40/17 Continental tires.

cjny · 11-21-2016, 05:58 PM

Yes, larger tires will measurably lower your gas mileage, but likely not that much. Consider other factors that might contribute.

Cjymiller · 11-21-2016, 06:17 PM

Quote:

Originally Posted by Kaotic Lazagna

I have the same mpg as the OEM wheels and tires when I have my 17x9 TC105N with 245/40/17 Continental tires.

This is because 17x9 on TC105N with 245/40/17 is almost the exact same weight as the stock setup.

wbradley · 11-21-2016, 06:20 PM

Heavier wheels/tires and more roll resistance arent going to reduce mileage by almost a third. And, there isn't the need for winter gas in FL. LOL

Im going to go with a heavy foot, multiple short trips and possibly the ethanol content of the fuel you used might be higher than previously.

VIP BRZ · 11-21-2016, 06:20 PM

That's way too large of a drop in gas mileage.. something is wrong

unless your car looks like this

C4RBON · 11-21-2016, 07:39 PM

TireRack measures fuel efficiency in their tire tests. The differences in efficiency between similar tires can be surprising. For example, there was a 5.3% difference between the best and worst tire in this Max Performance summer tire test:

http://www.tirerack.com/tires/tests/...y.jsp?ttid=218

Note that this test is done with tires of identical size.

Now if you were to go from a low rolling resistance narrow tire like the stock Primacy on stock wheels to a much wider, stickier, heavier tire mounted on heavier wheels, I would expect a significant reduction in fuel economy. The wheels and tires probably aren't the only factor, but I wouldn't be surprised if it accounted for 2/3 of the drop.

Kaotic Lazagna · 11-21-2016, 08:12 PM

Quote:

Originally Posted by Cjymiller

This is because 17x9 on TC105N with 245/40/17 is almost the exact same weight as the stock setup.

Lol. That was my point for the OP. It's hard for us to say anything without more info.

Kaotic Lazagna · 11-21-2016, 08:18 PM

Quote:

Originally Posted by wbradley

Heavier wheels/tires and more roll resistance arent going to reduce mileage by almost a third. And, there isn't the need for winter gas in FL. LOL
LOL.

http://www.platts.com/latest-news/oi...uests-21401095

They still receive varying blends of gas. May as well call it winter blend since it's different from summer blend.

df.dima · 11-21-2016, 09:12 PM

Quote:

Originally Posted by VeganGirl

Is this normal? Immediately after installing wider rims and tires(I'm going forced induction some time next weekish) I noticed my average kept dropping and dropping slowly over a few weeks. It was at a consistent 27-28, now it's 19-20 and will not go above 21. Is that normal?

I was getting close to 27-28 stock as well and with wider/stickier tire I get 24.5 (245 MPSS on x9 light weight wheel). Dipping beyond 20 seems pretty excessive, but depends on the way you drive I guess is possible, or you have some other factor. I can't imagine you drove aggressively and got 28mpg on stock, similarly, I expect you don't drive much different with wider tires now.

11-21-2016, 03:38 PM	#1
VeganGirl Senior Member Join Date: Sep 2015 Drives: Scion FR-S 2013 Location: Internet Posts: 142 Thanks: 11 Thanked 55 Times in 22 Posts Mentioned: 18 Post(s)	After putting on after market rims and tires my gas mileage went from 28 to 20? Is this normal? Immediately after installing wider rims and tires(I'm going forced induction some time next weekish) I noticed my average kept dropping and dropping slowly over a few weeks. It was at a consistent 27-28, now it's 19-20 and will not go above 21. Is that normal?

11-21-2016, 03:42 PM	#2
Tcoat Senior Member Join Date: Jul 2014 Drives: 2020 Hakone Location: London, Ont Posts: 69,838 Thanks: 61,656 Thanked 108,295 Times in 46,456 Posts Mentioned: 2499 Post(s)	Yes. Wait 'till you get FI on there! __________________ Racecar spelled backwards is Racecar, because Racecar.

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11-21-2016, 04:13 PM	#5
jasonojordan Senior Member Join Date: Jul 2013 Drives: 2013 satin white brz limited Location: Cottage Grove MN Posts: 1,049 Thanks: 162 Thanked 511 Times in 326 Posts Mentioned: 4 Post(s)	Well there are alot of things to consider here. 1. Whats the Size of the new wheels (Rims as you call them) 2. How much does the new wheels weight. 3. How wide are the new wheels. 4.How wide are the new tires? Thats the short version of the list of why did my gas mileage go in the shitter.

11-21-2016, 04:35 PM	#6
Kaotic Lazagna Senior Member Join Date: Apr 2014 Drives: GR Corolla Location: Lathrop, CA Posts: 4,943 Thanks: 3,096 Thanked 3,028 Times in 1,865 Posts Mentioned: 40 Post(s)	In addition to wheel weight and tire weight, you have to factor if the new tires have a higher traction rating than the tires they replaced. More traction means more grip, which means drop in fuel economy. One other consideration is the gas. Your area may have switched over to winter blend, which will give a drop in mpg. I have the same mpg as the OEM wheels and tires when I have my 17x9 TC105N with 245/40/17 Continental tires.

11-21-2016, 05:58 PM	#7
cjny Member Join Date: Jul 2016 Drives: 2016 BRZ Location: Upstate NY Posts: 69 Thanks: 18 Thanked 25 Times in 18 Posts Mentioned: 2 Post(s)	Yes, larger tires will measurably lower your gas mileage, but likely not that much. Consider other factors that might contribute.

11-21-2016, 06:20 PM	#10
VIP BRZ Senior Member Join Date: Mar 2016 Drives: 2014 Subaru BRZ Location: CA - San Fernando Valley Posts: 491 Thanks: 242 Thanked 333 Times in 179 Posts Mentioned: 2 Post(s)	That's way too large of a drop in gas mileage.. something is wrong unless your car looks like this

11-21-2016, 07:39 PM	#11
C4RBON Senior Member Join Date: Mar 2011 Drives: '15 BRZ, '19 GTI Location: USA/Iowa Posts: 204 Thanks: 79 Thanked 163 Times in 79 Posts Mentioned: 4 Post(s)	TireRack measures fuel efficiency in their tire tests. The differences in efficiency between similar tires can be surprising. For example, there was a 5.3% difference between the best and worst tire in this Max Performance summer tire test: http://www.tirerack.com/tires/tests/...y.jsp?ttid=218 Note that this test is done with tires of identical size. Now if you were to go from a low rolling resistance narrow tire like the stock Primacy on stock wheels to a much wider, stickier, heavier tire mounted on heavier wheels, I would expect a significant reduction in fuel economy. The wheels and tires probably aren't the only factor, but I wouldn't be surprised if it accounted for 2/3 of the drop.

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