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#1754432 - 01/24/10 10:37 PM Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16
oilcoholic Offline


Registered: 10/15/09
Posts: 182
Loc: Upstate South Carolina
A friend is putting new tires on his daughters Jeep Grand Cherokee, original tire size is 225/75R16. A plus zero size option is 235/70R16. I was telling him that I thought the 225's would be a little larger and that the Jeep might get better gas mileage if the 235's were installed. Looking at the tire calculator on Discount Tire, the 225's are .16" Sidewall Heighth higher, -.39" Section Width Wide, .34" Bigger in Diameter, 1.05" bigger in Circumference. The 225's also run -7.96 Rev. per mile Less. What do you guys think about these comparisons and gas mileage? The 225's are also about $100 less than the 235's. These tires are BF Goodrich Long Trail T/A Touring. I've just put some on my wife's Tribute of the 235 size. BTW, all things considered, I'm now thinking that these would be pretty close in fuel mileage, maybe negligible.


Edited by oilcoholic (01/24/10 10:48 PM)

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#1754562 - 01/25/10 04:45 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: oilcoholic]
ryan2022 Offline


Registered: 06/05/06
Posts: 1182
Loc: Calgary
I think at those sizes it would be a wash. With the 235's youd also have more rolling resistance, and the OD is very close anyway.
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#1754672 - 01/25/10 07:59 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: ryan2022]
mrsilv04 Offline


Registered: 12/08/06
Posts: 5890
Loc: Illinois
Those two sizes are close enough that it won't matter. The 235's are slightly wider. 7.96 extra revolutions, when you're looking at somewhere in the neighborhood of 700-720 revolutions per mile is nothing. That's 1 percent.

The 235's will look slightly "beefier" on the Jeep. That's all.
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#1754725 - 01/25/10 08:38 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: oilcoholic]
Quattro Pete Offline


Registered: 10/30/02
Posts: 23634
Loc: Illinoistan
Originally Posted By: oilcoholic
What do you guys think about these comparisons and gas mileage?

Like others said, the difference will be too small to notice.
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#1755322 - 01/25/10 04:13 PM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: Quattro Pete]
Kaboomba Offline


Registered: 10/05/09
Posts: 782
Loc: SE WI, USA
The difference in weight will erase any gains you would make via diameter. You would have to spin em up and drag em down in town, and on the highway you hafta shovel more air with em becuz they're wider. Really.

K
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#1755981 - 01/26/10 01:53 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: Kaboomba]
CrazyMike Offline


Registered: 01/03/07
Posts: 132
Loc: Central BC, Canada EHHH!
Same tread, same weight, same ply rating, just different 225/75 & 235/70 sizes, the 235/70's will net better mpg and slightly better acceleration. Depending on vehicle and conditions, it may be noticable.

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#1756321 - 01/26/10 11:15 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: CrazyMike]
oilcoholic Offline


Registered: 10/15/09
Posts: 182
Loc: Upstate South Carolina
My friend went with the 235/70R16. I rode with him 1st thing this morning. We looked at both tires and the 235's just looked "better" due to it's being wider. Our Tribute has 235's and he really likes the look of the BFG's on it and I think that was the selling point for him. It's a shame though, the 235's are $25 per tire higher than the 225's. Starting Sunday though, Discount Tire & BF Goodrich are offering a $60 MIR on 4 tires, that will help.

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#1757657 - 01/27/10 11:05 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: oilcoholic]
WishIhadatruck Offline


Registered: 05/09/06
Posts: 1245
Loc: Grand Rapids, MI
Too close to matter.
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#1761652 - 01/30/10 10:34 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: WishIhadatruck]
CourierDriver Offline


Registered: 12/27/09
Posts: 2875
Loc: Tennessee
I use what the door jam sticker says to use,,,one ton ram van e350 10ply,,,amen
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#1762144 - 01/30/10 04:50 PM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: CourierDriver]
rpn453 Offline


Registered: 11/06/02
Posts: 4840
Loc: Saskatchewan
I don't think the difference would be much, but I think the 225/75R16 would get better mileage due to lower tread mass, lower drag area, and taller effective gearing.
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#1776112 - 02/10/10 01:36 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: rpn453]
Ramblin Fever Offline


Registered: 06/28/05
Posts: 1627
Loc: Timberline
In all honesty, I have a '97 Isuzu Rodeo that came with 225/75r16's from the factory, I'm currently running 265/75r16's on it now, and have been for the last 7yrs.

I am the original owner of this truck and used the factory size for over 100k miles; currently sitting at 200k, the last 80-90k miles with tires 2 sizes bigger.

Truthfully, would you believe when I say there are NO differences in gas mileage between the 2 sizes. I've kept meticulous records on this truck, and have the mpg recordings of several tanks of fuel each month for the 13yrs of ownership...every entry is [censored] near the same, or perhaps 1-2mpg worse, or better.

contemplating between sizes as small as you're referring to isn't going to matter....not if I can go from a 29" skinny tire to a 32" wide tire plus wider rims.

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#1782048 - 02/14/10 10:02 PM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: Ramblin Fever]
CrazyMike Offline


Registered: 01/03/07
Posts: 132
Loc: Central BC, Canada EHHH!
That makes no sense Ramblin, a 3sp auto by chance, what is your gearing?

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#1782165 - 02/15/10 02:06 AM Re: Tire Sizes & Gas Mileage: 235/70R16 vs. 225/75R16 [Re: CrazyMike]
Shannow Offline


Registered: 12/12/02
Posts: 25365
Loc: a prison island
Maybe the mileage improvement is taken up by the reduction in indicated miles.
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