Fuel mileage going from stock wheels/tires to larger tires

[1997XLTRollover]

Ok guys I'm about 3 millimeters away from losing my mind with my 96 and the fuel economy I'm getting. That being said I'll get right to the point. You guys that went from stock tires to something larger (prefer 32's since that's what I have) what was your fuel economy before and after?

State your setup too, engine, trans, 2 or 4 wheel drive and what gears you have. If you changed gearing at the same time as tires please state that too. Also please state true fuel economy, so if you didn't change your speedo gear please factor that in because it will obviously read a false low if you never changed it.

My truck is a 96 5.0 with the 3.73 gears. I'm getting 10/13 with my 32x11.50 6 ply tires. My old 99 got 17/19 on the stock 30" tires and I can't believe a set of 32's on my 96 would make it get 10/13. I unfortunately have no stock tires I can put on for a week it to see what I get with stock wheels and tires, otherwise I would just do that.

TIA

 

[Spoon91]

Hey Roll,
I have a '97 5.0L 2wd running a 3.73 gear with a 2in Suspension lift and a 1in body lift on 33's and even with my Utility basket that weighs around 250lbs I still get high 14 low 15 MPG.

The fact that your AWD could play a part in things.....Maybe.

 

[1997XLTRollover]

Hey Roll,
I have a '97 5.0L 2wd running a 3.73 gear with a 2in Suspension lift and a 1in body lift on 33's and even with my Utility basket that weighs around 250lbs I still get high 14 low 15 MPG.

The fact that your AWD could play a part in things.....Maybe.

Is that highway or city miles? Also I agree my AWD probably drops 1 mpg or so over what you would get.

 

[Spoon91]

Is that highway or city miles? Also I agree my AWD probably drops 1 mpg or so over what you would get.

A little of both but most of it is city sense I don't drive her to work very much. It just runs around town on the weekends for the most part.

 

[1997XLTRollover]

A little of both but most of it is city sense I don't drive her to work very much. It just runs around town on the weekends for the most part.

Had a feeling. We'll see what everyone else chimes in with with but I think my truck has something wrong with it. There is no way I should be getting 13 or even 14 mpg straight highway, and that's if I baby it. I would expect at least 17.

 

[Spoon91]

It's just me asking but when was the last time the Plugs/Wires and Fuel Filter were changed? You could also clean your Mass Air Sensor and I've changed my Air/Idle control valve as well. Not sure if any of that would help.

 

[1997XLTRollover]

It's just me asking but when was the last time the Plugs/Wires and Fuel Filter were changed? You could also clean your Mass Air Sensor and I've changed my Air/Idle control valve as well. Not sure if any of that would help.

5k miles ago when the engine was completely rebuilt form every sensor to new lifters and valve springs etc. MAF has been cleaned and so has my IAC but if my IAC was bad how could that effect my fuel economy? Because honestly my truck does every so often drop too low RPM wise when I drop it into drive and I can't for the life of me get my IAC to run at more than 8% at idle when warmed up.

 

[Spoon91]

Well Dang.....
I was just hoping that it could be something simple like that

Mine idles around 750/800 as well but gets "OK" mpg
I'm sorry Roll but I just don't know what it would be Homie.

 

[1997XLTRollover]

Well Dang.....
I was just hoping that it could be something simple like that

Mine idles around 750/800 as well but gets "OK" mpg
I'm sorry Roll but I just don't know what it would be Homie.

Yeah mine is there most of the time too. It seems to run ok now in all honesty apart from the bad MPG. I could get into all sorts of garbage but here this is why I'm getting frustrated. Notice the start date of that thread.


http://www.explorerforum.com/forums/showthread.php?t=423495

 

[Spoon91]

Yeah Brother, Over a year does suck.....Bad!!!

 

[1997XLTRollover]

Yeah Brother, Over a year does suck.....Bad!!!

Yeah and all the BS troubleshooting aside, you know what it's like having to fill your tank every 150-175 miles? lol Expensive and annoying. Thank god gas prices aren't 4 bucks a gallon still.

Anyway back on track with tires sizes and MPG changes. haha

 

[Spoon91]

Yeah and all the BS troubleshooting aside, you know what it's like having to fill your tank every 150-175 miles? lol Expensive and annoying. Thank god gas prices aren't 4 bucks a gallon still.

Anyway back on track with tires sizes and MPG changes. haha

I hear ya Bro.
When I was driving my EX to work I would fill up every Monday/Wednesday and Friday..... Annnndd that's why I got my new '16 Accord Sport.
Helps with gas, Keeps wear and tear off of the old girl and it puts me back in a Honda where I started almost 20 years ago.

I'll keep up with what others say because I've been thinking as to what it could be too.

 

[SoHK_alumni]

Not exactly apples to apples:

1996 Expo 5.0 rwd in my Ranger.

Box stock 5.0/4R70W except for Torque Monster headers.

235 55 17 tires -- just over a 27" tire, 3.27:1 gears

2050 RPM at 70 MPH.

4450 lbs total daily carry.

15.5 MPG daily driving with <50% highway, 22.5 MPG level cruise at 70.

 

[1997XLTRollover]

Not exactly apples to apples:

1996 Expo 5.0 rwd in my Ranger.

Box stock 5.0/4R70W except for Torque Monster headers.

235 55 17 tires -- just over a 27" tire, 3.27:1 gears

2050 RPM at 70 MPH.

4450 lbs total daily carry.

15.5 MPG daily driving with <50% highway, 22.5 MPG level cruise at 70.

Did you ever jump up in tire size? My main question is how bad does a jump in tire size hurt mpg on a V8 Explorer. My truck was rated 14/18 from the factory which I feel is accurate, so in essence I have a solid 4 mpg drop in fuel economy just from tires? I highly doubt that's the case.

 

[SoHK_alumni]

What kind of RPM's you running at high way speeds?

My higher ratio gears with smaller tires should about even out with your lower ratio and larger tire.

 

[1997XLTRollover]

What kind of RPM's you running at high way speeds?

My higher ratio gears with smaller tires should about even out with your lower ratio and larger tire.

Actually probably pretty close to you because with 3.73's and the 32's it would be as if my truck had 3.27's from the factory. Tires are 48lbs and wheels are around 30 I believe. Stock wheels are maybe 20 and stock tires are around 35lbs. So rotational mass quite a bit more and is also moved further out on top of being a gear reduction. So I know it will hurt MPG I just can't see it hurting it this much so was hoping I was not the only guy with a 5.0 explorer running on 32's.

 

[Ritsui]

You didn't mention what mileage you were getting before or what TYPE of tires each were.

I'm getting 9 to 13 on the road (factory was 15-18), but that's after sliders, skid plate, locker, body lift, larger/more aggressive tires.... all of which have some affect on mileage. Anyway, all told I think the biggest drop for me wasn't going up in size, but changing tread pattern from street to an aggressive AT. There is substantially more rolling resistance in an MT or AT tire.

 

[1997XLTRollover]

You didn't mention what mileage you were getting before or what TYPE of tires each were.

I'm getting 9 to 13 on the road (factory was 15-18), but that's after sliders, skid plate, locker, body lift, larger/more aggressive tires.... all of which have some affect on mileage. Anyway, all told I think the biggest drop for me wasn't going up in size, but changing tread pattern from street to an aggressive AT. There is substantially more rolling resistance in an MT or AT tire.

I never had stock tires on it or I wouldn't have had to post this thread haha. I know with my 99 I got 19 highway easily and it had 160k miles on the original spark plugs. But my main question is what did people see when changing from a stock tire to a larger tire. I just can't see me going from say 18 or 19 highway to 12 to 13 highway just by putting a 32" AT on it. Although that is an interesting tid bit about the tread and the rolling resistance of an AT and MT tire.

Hell, my frickin 5300 lb 98 F-150 with 32's gets 16 and it has 240k miles on it and 3.55's. Granted I know different animal, but I just can't believe I should be getting 13 with my ex.

 

[1997XLTRollover]

You didn't mention what mileage you were getting before or what TYPE of tires each were.

I'm getting 9 to 13 on the road (factory was 15-18), but that's after sliders, skid plate, locker, body lift, larger/more aggressive tires.... all of which have some affect on mileage. Anyway, all told I think the biggest drop for me wasn't going up in size, but changing tread pattern from street to an aggressive AT. There is substantially more rolling resistance in an MT or AT tire.

Now here's an interesting read.

http://www.fourwheeler.com/how-to/wheels-tires/129-1104-tires-and-fuel-economy/

 

[Ritsui]

I know with my 99 I got 19 highway easily

Hard to compare two different trucks from different years... even of the same model. There are just too many variables. I'm pretty sure I never got 19 on my sport from the factory.... but the SOHC6 4WD is a completely different beast than your AWD V8 so to some extent my mileage means nothing .

To get back to the point... I doubt a 1-2" change in diameter and/or tread pattern could be responsible for a 40% drop in gas mileage. I'd guess (before running off to read your link and others...) 10-20% max. There are certainly multiple factors involved in the difference.