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Discussion Starter · #1 ·
OK I have a 2012 Ford Focus SE with a manual tranny. five speeds.
The top gear is overdrive 0.81 with a final drive of 3.82

The auto tranny has a top gear with an overdrive of 0.702 and a final drive of 3.85
So i really want to get the lower RPM (equal to the auto trans sixth gear) of my engine at freeway speeds in fifth gear manual tranny
My idea is to stick 215. 55.17 tires on my 17" wheels. (26.3 diameter 793 rev per mile
The stock tires are 215.50.17 25.5" diameter 818 rev per mile

This is a 3.15% increase.
I also have to say first gear is pretty low in the first place. raising it also would be zero problem IMO.
The whole general raising of the gears would be fine by me.
The speedo error is not a problem, as i drive the speed limit, and really do NOT speed like five ofer ten over.. so having it be a little on the high side in NOT gonna be an issue (no one else drives the car.. 50mph indicated would be about 52 real mph, and that is assuming the speedo is exactly correct, instead of the usual a little below the real speed.
So aside from general compaints about any and everything about this, any problems one would see doing this?
The tires would Continental Extreme contact DWS (from Tire Rack naturally)
 

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Im not an expert in the area, but ill try to give my best info.

As of currently, every manufacturer is in a race to get the absolute best mileage out of their cars. Ford being one of them. Im fairly certain that they took this into account when they were designing the new focus. One of the problems with larger tires is that the are heavier, and heavier tires tend to take more power to push.

Also, remember that rpm is only a small part of what makes mileage, the larger part of this is engine load. I can get better mileage in my SVT at 3000rpm than i can at 2500rpm, mostly because at 2500 rpm, my engine is producing less torque and thus under more pressure to keep the car moving.


Finally, id worry about wheel well clearances, the larger the tire, the easier it is to rub.


Honestly, if you want to get better mileage, i think the best way to go about it is to sacrafice your handling a bit and go for a harder compound skinnier tire.


Sources - (ive managed over 40mpg in a stock SVTF)
 

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And if your current tires aren't worn out, I doubt you'd save as much on gas (if any, see first reply) as it would cost for the new tires...........
 

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You should be able to see a 6-7% gain by increasing the tire pressures to 40-42 PSI...just be sure you like the ride and handling.

Maybe a 5% gain by installing LRR (low rolling resistance) tires. Continental makes good ones...OEM size...or one size larger?

An Ultragauge might gain you 15%...depending on how you drive now.

The manual version of the car does better than the auto version mpg wise?
 

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You should be able to see a 6-7% gain by increasing the tire pressures to 40-42 PSI...just be sure you like the ride and handling.
When over inflating the tires, you are also at higher risk for tire damage from potholes and uneven tire wear. Also, over inflating the tire decreases the amount of tire that makes contact with the road. The savings on gas from the harder, over inflated tire probably wont out weigh the cost of a tire repair/blowout or having to replace them earlier. I am not sure how much higher 40-42 is compared to the Ford recommended for the new Focus, so I'm not sure if that's like 4psi higher or 14, ect..
 

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It shouldn't be a problem to go with the taller tires from a usage standpoint. My winter tires are 205/60R16, which are slightly taller than the OEM 215/55R16 all-season tires the car came with.
 

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Would it have been cheaper to buy a hybrid rather than a 2012 focus? Sure are posting alot about mileage. Between special aero rims and now tires? The skinner taller tires give less effort to turn but the company's test alot to pick the tires that best suit the vehicle. U may gain hwy performance but then lack in cornering with sideway flex which could loose control.
 

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Discussion Starter · #8 ·
I already use 41psi front, 36psi rear inflation pressures.
I probably will go to 44 front and 37 rear..
All this about tire pressure was covered in another thread. between the 'yeah it works' and the nooo you will die because Ford knows best threads.. it got tiring fast.
My real only worry is the clearances, and if i do not like it, then the waste of $550 for tires I do not want anymore.
And buying really good tires, even though the old ones are not worn out is not a waste to my thinking. having REALLY good tires is important. IMO.
And the difference in 5% of series is not going to harm the handling... I am not street racing the Grand Prix every day here...
 

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I don't follow what psi it says on the door. I go by what is says on the tires its self. Every tire is different -how many plies the sidewall is and what reinforcement they have. But I wouldn't go over what the tire says. Filling up tires at 44psi cold and driving on them could get 50psi or so hot and even hotter on a road trip and having a blow out could rip apart the whole side of the car a cost thousands on a new car which wont be covered by warranty. So be careful. My falken azenis I ran about 43psi and the max was 50psi. My hankook rs3's are run at 38-40.
 

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Not to be an a$$ with my second post, but I think you're making way more of this than what you could possibly get from it.

First of all, final drive "ratio" is exactly that. It's a number 'x'-to-1, which represents teeth on the transaxle, blah blah... Accordingly, one divided by a smaller number turns the engine slower. So with your numbers, your 5-spd is actually more efficiently going down the road than the automatic. Barely.

Similarly, increasing tire size within the confines of a Focus wheel well to the point of making a noticibly slower rate of drivetrain rotation isn't likely at all. On larger vehicles than this can actually be experimented with, you're talking about several sizes taller to ever notice a few MPH on the speedo. And that's how you can tell that the motor is turning slower, because so too does the speedo.

Sorry but that not gonna happen by anything more than making the tires rub the fenders for a zero mpg gain and net loss in drivability with a car this size.

Have a nice day;)...
 

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Lets try putting some reasonable numbers to this tire swap theory. Assume a car gets 40mpg and gas costs $3.50 a gallon. Now lets add those so called 500.00 (price for sake of calculations only) gas saving tires to the car and lets say they result in a 5% increase in gas mileage (which is optimistic from everything I've read but I'll use it anyway). That results in a fuel mileage increase of 2 mpg. At 40 mpg the cost per mile is 8.75 cents. At 42mpg the cost is 8.33 cents per mile. At that savings (.42 of a cent per mile or .0042 cents) you would have to drive those new tires over 119,000 miles to pay for them (or longer if the tires cost more).

So in summary, if you're trading a good/decent set of regular tires for the so called fuel efficient ones, the swap can't really be justified from a realistic economic standpoint (but hey, who's to say what is realistic.....I do know that 500.00 will also buy 5700 miles of gas using the same numbers above).

Everything has a price that has to be taken into consideration. While increased PSI may result in a mpg increase, there's also a cost associated with increased tire and suspension wear, for example, that results from that increase that must be considered as well. That said, the only no cost mpg increases come from a lighter right foot.
 

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With my 03 where the 205/50 16s are supposed to be at 35 PSI..I run them at 40-42 PSI....in winter I might drop them a few lbs.

I'm transitioning to LLR tires with 2 Kumo Ecowings on the back. Current front tires are flat spotted and make a lot of noise.

I use a Scangauge. I monitor realtime mpg vs avg mpg...and TPS to know where the throttle is...this allows you to see how your driving decisions affect your mpg.

In her case...it's not really cost effective to totally change tires IMO. Most effective would be the Ultragauge.

Then there are certain fuel additives that might work...but you need to pay attention to cost.

I have consistently seen 35 mpg mixed tank to tank this summer with a car rated at 24 mpg mixed EPA....but I try hard. My real world baseline was around 27.5 mpg with late spring weather and winter gas....so the gain is only around 27%.

* as far as tire pressures...they are always inflated COLD...and are expected to gain pressure when hot. I've heard of people running them at 50-60 PSI...but I stop at the sidewall MAX...besides 40-42 is a rough enough ride.
 

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Another way is to make the engine work less for power too. An intake and exhaust help out. The less the motor struggles to get air in and air out is more efficient. But this also cost money if ur already pinching about gas I doubt ur going to buy performance parts. I've done 3 cars and have seen mpg improvement my 06 duratec 5spd,my buddys and I svts 6spds. See if any new 12's have gained any mpgs through an intake
 

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Discussion Starter · #14 ·
Another way is to make the engine work less for power too. An intake and exhaust help out. The less the motor struggles to get air in and air out is more efficient. But this also cost money if ur already pinching about gas I doubt ur going to buy performance parts. I've done 3 cars and have seen mpg improvement my 06 duratec 5spd,my buddys and I svts 6spds. See if any new 12's have gained any mpgs through an intake
I am not interested in MPg because of gasoline costs.
Rather it is just a new hobby.
I used to just drive XX over the speed limit. It made driving interesting.
Now, I do not want to go fast. So concentrating on MPG is another way to 'do' something while driving so I do not just get bored.
Spending money is not a problem.
I might buy other tires anyway.... just because i am a big believer in using the best tires i can on my car.
The OEM Conti's suck in Winter anyway. (per Tire Rack info) The Conti's i want are decent in Winter...(besides being #1 in that type of tire..)
Pretty much the only issue that matteres a LOT is if the tires would rub. Then it would be a real BUMMER.
I do appreciate the other comments, especially the one working out what stuff would cost. i often do taht to give another point of view of an issue. So thanks.
 

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sorry double post
If you see it as a hobby...check here:

http://ecomodder.com/forum/

.....there are other good sites also. You need to avoid most sites that don't deal directly with mpg issues....you'll just go round and round.

I also see the mpg game as a hobby...sort of like trying to make a car go faster...only your focus (so to speak) is mpg...same kinds of technical issues.

I do tend to be sort of cheap...and expect what I do to be cost effective...or close to it....or so I say. In the end...you have to do your research and then try things.

There is a lot of snake oil out there (things "they" claim work to improve mpg)...your mission...should you decide to accept it...is to figure out which is which.

Remember...they don't give those mpgs away...they are hard to find.
 

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Discussion Starter · #18 ·
Have you tried texting?!!?[woot]

Nooooo. First i do not even own a cellphone. I an a true luddite. Cellphoneless in an age where every human has one implanted in thier head.

When i used to drive fast, i didn't even have any music playing. Just me and the road. Now i can play music, watch the mpg meter, and laugh at all the folks pissed at me for driving like a little old lady. (which i am!)
I used to be "the Beach Boys: "Little Old Lady From Pasadina".. driving my SVT..

Now i am just the little old lady from Palmyra: ""Why is she driving ten MPH BELOW the frickin' speed limit?"" [angel]
 

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Nooooo. First i do not even own a cellphone. I an a true luddite. Cellphoneless in an age where every human has one implanted in thier head.

When i used to drive fast, i didn't even have any music playing. Just me and the road. Now i can play music, watch the mpg meter, and laugh at all the folks pissed at me for driving like a little old lady. (which i am!)
I used to be "the Beach Boys: "Little Old Lady From Pasadina".. driving my SVT..

Now i am just the little old lady from Palmyra: ""Why is she driving ten MPH BELOW the frickin' speed limit?"" [angel]
LOL! As long as you're not in the Fast Lane![cheers]

I'm not even sure how to do that! You must have an 85mph speed limit or something!!!!:D
 
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