Tire size vs. mpg - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 31 (permalink) Old 01-04-2011, 05:14 PM Thread Starter
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Tire size vs. mpg

So I bought my truck with 305/70R16s on the stock 16" rims. They are LRC or D and actually have less load capacity thatn the OEM 265/75 LRE tires. They are the standard BFGoodrich AT tires. They are nearing the end of their life and I tend to overload the truck and like long tows with an RV so I want good tires. I have 3.73 gears and an auto.

The choice I have is between 285/75 and 265/75 tires.

My question is, what mpg differences can I expect to gain by downsizing to 285 or 265 tires. I have chosen the General Grabber HTS all season highway tires with "Low Rolling Resistance".

Are the 265s the ideal mpg tire?

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post #2 of 31 (permalink) Old 01-04-2011, 07:06 PM
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Re: Tire size vs. mpg

When I went from 315s to 285s, I really didn't notice that much of a difference. Maybe a mile per gallon.

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post #3 of 31 (permalink) Old 01-04-2011, 10:11 PM
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Re: Tire size vs. mpg

From what I can tell, either 265-75x16 or 235-85x16 are the optimum sizes for MPG.

Hey! One MPG for just tires is a nice difference.

Be sure and recal your speedo.

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post #4 of 31 (permalink) Old 01-04-2011, 10:16 PM
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Re: Tire size vs. mpg

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Originally Posted by Dave Whitmer View Post
From what I can tell, either 265-75x16 or 235-85x16 are the optimum sizes for MPG.

Hey! One MPG for just tires is a nice difference.

Be sure and recal your speedo.
True, it does add up. But I didn't really pay attention to it because I'm not sure how much the odometer was thrown off by the bigger tires.

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post #5 of 31 (permalink) Old 01-05-2011, 03:18 AM
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Re: Tire size vs. mpg

My best mpg experiences have came from BFG rugged trails. Also, the wider tire will get worse mileage (the 285s) not going to affect it by much, but I'd say 1 mpg is a good estimate

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post #6 of 31 (permalink) Old 01-05-2011, 03:24 AM
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Re: Tire size vs. mpg

285's are the same height as your 305's just a little narrower. The 265 is narrower and smaller just fyi

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post #7 of 31 (permalink) Old 01-05-2011, 01:21 PM
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Re: Tire size vs. mpg

You should have no problem getting 1 or 2 more mpg with the 265's. I lost about 4 mpg when I went from 265/70/17 to 375/50/18. There is a ton more unsprung rotating weight.

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post #8 of 31 (permalink) Old 01-05-2011, 02:43 PM
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Re: Tire size vs. mpg

How much difference do you guys think there is in like an AT tire versus like a highway tire?

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post #9 of 31 (permalink) Old 01-05-2011, 05:49 PM Thread Starter
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Re: Tire size vs. mpg

Perfect info, it was what I had read elsewhere but more specific to our engines and gear ratios. The height difference (305/70 to 265/75) is very small, like less than an inch overall, but the width is 40 millimeters. I would like to bump up my RPMs for a given speed a bit as well but I don't expect the speedo difference to be much, like 4% or 2 mph at 50 mph.

1 mpg is a big deal for a big truck. It's between a 5 and 10 % improvement.

Easier on brakes, our unit bearing hubs, and the steering system as well.

2000 F350 SRW, 4wd, CCSB, PSD
Lowered rear end to F250 height, 4" exhaust w/ muff, foil delete, AIH delete, Ford AIS intake, tru-cool trans cooler, autometer under dash pod and gauges, Mile Marker hubs, 04 headlights, soft tonneau

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post #10 of 31 (permalink) Old 01-06-2011, 01:35 AM
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Re: Tire size vs. mpg

A green web site did an extensive test on tires and MPG for all size vehicles. At the time the BFG Long Trail 245s gave the lowest rolling resistance for pickup-sized vehicles. Don't know if that's still true or not.

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