INSTALLED 14" WHEELS - MPG IS WORSE??

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Ace
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My tercel:: '83 DLX 4WD Tercel wagon 3AC

Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Ace »

I've always had stock 155-80R-13 tires on my '83 Tercel.When my car was newer I used to consistently average about 36 MPG on the same drive between Oregon and Oakland CA. I was doing the same drive at regular intervals for a year so it was a reliable check. I have logged every tank of gas I've put in this car since I bought it in 1984.

My driving is more sporadic now so my mileage is generally less, but nearly always over 30 MPG with mixed driving. I suspect the higher levels of ethanol in gasoline these days is reducing my MPG somewhat.

It took me a long time to figure out, but I believe I was getting possibly 10% lower mileage using cheaper brands of gasoline. I finally noticed that, after the long consistent drives that I used to do. When I log my gasoline fill-ups, I also note the brand.
TominMO
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My tercel:: 1986 SR5
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by TominMO »

Here is a tire diameter calculator from Miata.net: http://www.miata.net/garage/tirecalc.html
1986 4WD Tercel, formerly gold, now camo
1995 Ford Aspire SE, MPG development car, shooting for 65 MPG hwy
1990 Ford Festiva, mild motor swap, HP development car
The other Tom M. in STL w/a gold 1986 SR5--from the universe where Spock has a goatee
Housewiz
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My tercel:: 1987 4WD SR5 wagon

Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Housewiz »

Would any of you guys have an answer why after installing 14" wheels/tires we are getting less MPG? I made the switch due to the motor RPM's being so high at 65 MPH.

Thanks,

Steve
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dlb
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by dlb »

yes, that's what this whole thread is about, housewiz. you even started it. remember that we determined your larger tires made your speedo and trip meter inaccurate, and you had to account for the difference in overall tire size when calculating speed and fuel economy? give the thread a read over from start to finish and you'll see it.
TominMO
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My tercel:: 1986 SR5
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by TominMO »

You will get worse mileage in stop-and-go city driving, because the heavier tires take more energy to get up to speed. Ideally we would have light tires/wheels for everyday driving (155/80x13) and taller tires (on aluminum rims to minimize weight) for hwy driving, esp. cross-country. But on cars as non-aerodynamic as our T4s, the best way to increase MPGs is simply to slow down and drive in the highest gear feasible.
1986 4WD Tercel, formerly gold, now camo
1995 Ford Aspire SE, MPG development car, shooting for 65 MPG hwy
1990 Ford Festiva, mild motor swap, HP development car
The other Tom M. in STL w/a gold 1986 SR5--from the universe where Spock has a goatee
tercel4wdrules
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by tercel4wdrules »

Best mpg I have logged was at lower speeds - between 50-60 mph. I just have to find a slow truck and go behind it to give me an excuse to go that slow. If there's no one going slow in the far right lane, then I have to go at least the speed limit, which is usually 65, with some stretches down to 55 mph, but even then everyone is going 65.
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Housewiz
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My tercel:: 1987 4WD SR5 wagon

Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Housewiz »

Our '87 wagon w/69K miles, 14" Ford Escort wheels and hubcaps.
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Petros »

where did you find a T4wd with only 69k miles? that is really worth good money around here. looks like, good trick there too, must have tires with extra good traction to do that!
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
Housewiz
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My tercel:: 1987 4WD SR5 wagon

Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Housewiz »

The wagon started life in Santa Fe, NM. Then driven to Vt and sat in a garage for 10 months a year - used only 2 months each summer. Just brought it here Spring of '12. Didn't like the motor whine/high revs so we did the 14" wheel swap. Didn't improve the mileage but dropped the cabin noise and looks much better than the stock wheels.

Tell me what you think the value is where you are. We paid $1K.

Steve
TominMO
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by TominMO »

Housewiz wrote:The wagon started life in Santa Fe, NM. Then driven to Vt and sat in a garage for 10 months a year - used only 2 months each summer. Just brought it here Spring of '12. Didn't like the motor whine/high revs so we did the 14" wheel swap. Didn't improve the mileage but dropped the cabin noise and looks much better than the stock wheels.

Tell me what you think the value is where you are. We paid $1K.

Steve
You paid $1K?!?!? You stole it! :lol:

I wonder why someone would buy a 4WD and only use it two months in the summer?
1986 4WD Tercel, formerly gold, now camo
1995 Ford Aspire SE, MPG development car, shooting for 65 MPG hwy
1990 Ford Festiva, mild motor swap, HP development car
The other Tom M. in STL w/a gold 1986 SR5--from the universe where Spock has a goatee
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Petros
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by Petros »

I think I remember the story, it was left at their "summer house", vacation home. and only used when they were there.

A really low mile T4wd sold on ebay a few years ago for $10,800. Has something like 36k original miles and looked show room new. I have sold several decent daily drivers in good mechnaical condition for $2,500 each in the last three years (project cars that all need repairs that I fixed, but were in otherwise good condition). these were daily drivers that were by no means in show room condition, but everything worked and had lots of new mechanical parts. they had just under 200k miles. low mile clean ones sell for about $3500. Occasionally someone tries to get $5k for one that is not that nice (they either do not sell or they lower the price drastically), but that would not be an unreasonable price for yours with that low of miles. Paying only $1000 is a real bargain.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
specialtee
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My tercel:: 1983 4wd Wagon SR5

Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by specialtee »

MR2Di4 wrote: Sat Sep 29, 2012 11:23 pm Remember that you're not driving a muscle car and if you've increased the diameter, rolling resistance, and possibly the weight at each wheel your engine is having to work harder to make revolutions. Harder work means more fuel burnt. The 3A-C isn't exactly a torque monster, so seemingly small changes can have a big effect.

MR2Di4 8)
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by xirdneh »

I have a collection of speedo units, the part with the plastic gear on the end that plugs into the bottom of the tranny. Some have 20 teeth some 22 and maybe some other amounts. I wonder if swapping out would help with the tire diameter change. Someone with better math skills could figure that out. I wil check them out to see what other numbers of teeth there are. Probaby came from 2wd sedans
Love those Tercell 4x4 wagons but they sure suffer from road noise.
xirdneh
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by xirdneh »

17 teeth, 19, 20 and 22 is what I have
the 20 tooth is on the early 4wd trannys 22 on the later
Love those Tercell 4x4 wagons but they sure suffer from road noise.
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NWMO
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Re: INSTALLED 14" WHEELS - MPG IS WORSE??

Post by NWMO »

xirdneh,

Are we able to change just the plastic gear or does the entire cable need changed? Either way, a 20 tooth in place of a 22 would likely improve speedo accuracy for the 4.11 gearing with 14" tires I believe, assuming the gear is part of the cable end. I believe on some older cars (60s and 70s) you could switch a gear on the side of the tranny to adjust speedometer readings.

Chris
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