Gas Mileage dropped like a rock

[Supra725]

from my house to SFO was 95 miles one way.

I drove 70 mph with the ac on and 4 50 lbs luggage.

Cruise control on most of the way..

 

[Spencer]

i use a fuel tracker app on my iphone

i was getting an average of 14 with my 31"s

now with the 285/70's im averaging 11mpg
=/

i had a similar setup.

3" LIFT
2" BL
285/75/16s

I averaged 17MPG..

With my Land rover its 14MPG..

AND THATS WITH 235/75/16 AND NO LIFT.

 

[Romano]

can anyone tell me why i am only getting 175 miles out of one full tank
i have a 1996 2wd v6

 

[durrell]

I average 305 miles per tank, and that's with about 1.5 gallons to spare. I usually put just over 17 gallons in.

I'm averaging a little over 17 MPG and that's with 32's.

 

[JohnsD90]

My MPG is not good anymore, but i drive with a heavy foot now, oh well, the jetta is for when i want mpg. I used to get 20, now its way less.

 

[piperoo]

Weird...I was getting 320 miles on a tank...now that I got different tires I am getting like 270 miles...the tires aren't even that much larger! Plus I replaced my spark plugs, new 02 sensor, cleaned the MAF....I am getting around 16-17 mpg now...

 

[WrexHAmm]

Wow! Wow! Wow! 175 miles... 190 miles to a tank.... 240 to a tank.... I have never got less than 300 to a tank. You boys need to get out there and starting clean and replacing. That ain't right.

I average about 320 with 25/75s BF AT and no other mods. It might be a direct reflection of higher mileage vehicles? I know over time you guys with 140K + will get build up and parts will just naturally wear/ get dirty. I just hit 90K with an 01 and the mileage only changes slightly when I drive in the mountians.

I just make sure my tires are properly inflated, clean air filter, just changed plugs and I don't floor it off the line. The hard acceleration is what kills mileage.

Other than that I would do some hard searching and find every improvement for gas mileage possible. Spend the time and money to SAVE money. You're just throwing about cash everytime you fill up.

 

[larrylegend]

How many miles you get per tank has nothing to do with gas milage. If your gas gauge is off at all, which is a common problem with these vehicles, then your miles per tank will vary. There are widely varying reports of how many gallons are needed to "fill up" a tank. Some folks fill up when the light comes on and only put in 15 or 16 gallons. Some folks put in 17 gallons. It all depends on your gauge. I get about 18mpg with a mix of city and highway with Duratracs in 265/75/16. I also have the deckplate and new plugs and wires.

 

[panzer]

MPG Math Question

Anyone know the math behind putting on larger tires while not getting the spedometer updated. Basically, when we put larger tires on our trucks most don't correct the spedometer to factor in the larger tires. On my truck I went from stock 265/70/r16 to 285/75/r16. For each revolution of my tires I go an additional 7 inches now versus what I did with my stock tires.

That being said, if I now go 250 miles on a tank of gas I'm actually going farther than that because my spedometer thinks I have smaller tires (stock) when I really have my larger tires (285/75/r16).

Anyone figure out the math that says how many miles you truely went on the larger tires? Example: 250 per tank is really 262 (or whatever) on my larger tires.

I started playing with the math in Excel to find out that I don't have the patience/smarts to figure this out. Thanks.

 

[panzer]

MPGs with Larger Tires

Just answered my above question by doing some more research. Here is what I found...

My 285/75/r16 tires are 7" more in circumference than my stock 265/70/r16s.

This means my 285s have 7.27% more circumference than my stock tires.

So when calculating my MPG on a tank of gas I need to figure that my spedometer is actually off (lower) by 7.27%.

If my odometer says X I really traveled Y on the tank of gas (X * 1.0727 = Y):

X Y
220 236
225 241
230 247
235 252
240 257
245 263
250 268
255 274
260 279
265 284
270 290
275 295
280 300
285 306
290 311
295 316
300 322
305 327
310 333
315 338
320 343

This will need to be factored into your MPG calculations, if not, it will appear that you're actually getting less MPGs than you truely are... making it look like your larger tires are more of a detriment to your MPGs than they really are.

 

[Deceptiwave]

So, math really can be helpful?

 

[cj80cruiser]

can anyone tell me why i am only getting 175 miles out of one full tank
i have a 1996 2wd v6

Because you're pulling a boat anchor down the road with your emergency brake on to and from work????

Tell a little more about your truck. When did you get it, what mods have you done, suspension?, tires?, tune up? etc......

 

[Spencer]

anyone know the math behind putting on larger tires while not getting the spedometer updated. Basically, when we put larger tires on our trucks most don't correct the spedometer to factor in the larger tires. On my truck i went from stock 265/70/r16 to 285/75/r16. For each revolution of my tires i go an additional 7 inches now versus what i did with my stock tires.

285/75/16 = 32.8
265/75/16 = 30.6

32.8/30.6 = 7.1%

30MPH X 7.1%= 32.1
70pmg x 7.1%= 74.91

 

[Spencer]

It might be a direct reflection of higher mileage vehicles? I know over time you guys with 140K + will get build up and parts will just naturally wear/ get dirty.

No, 200,000 miles and I still averaged 18mpg with 3" lift and 17mpg with 6" lift and 33"s