# Recomended tire size for best MPG



## zakezuke (Mar 22, 2003)

I currently have a 1988 sentra base model with 13 inch wheels. I'm wondering if anyone has done some research as to which tire size offers the best efficency for freeway driving for this car.

I'm sure the 13 inch wheel is none too popular, but hey I'm cheep. .


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## BadAhab (Apr 30, 2002)

Go with the lightest weight hardest compound stock size tire you can find. Anything wider is going to increase rolling resistance and lower mpg. If you really wanted to go crazy you could go with the talliest skinniest tire you can find... but then your spedo would be off and you would look like a tard. Your going to see better gains in mpg by taking good care of the motor then you will with tires.

-sean


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## zakezuke (Mar 22, 2003)

I generally do keep good care of the motor... except that spare one in the back yard, but I don't think that counts.

But I have noted in the past the best gas milage I ever got were on cheep ass tires. Some brand called Lemmans or Lemmings or something like that, and i'm thinking they were 165r70s or some such. 

But I know the theory of traction = friction... just curious as to what diamater as well as width seems to work the best as far as mpg go.


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## bahearn (Jul 15, 2002)

The driver makes the biggest difference. That said, keep your tires inflated.


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## pearsont74 (Oct 1, 2002)

Id think the weight is the only difference
for example...my stock 13" steelies weigh almost the same as my 17" BSA 210 with 215/R40

with our GA16DE engines though...they get great MPG, I wouldnt worry much about the tires taking away from MPG


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## niky (Jul 20, 2002)

differences are in weight, rolling resistance and inflation.

smaller rims or lighter rims = less weight, less rotational inertia = better mpg

stock tires or skinnier= less weight+lower rolling resistance (smaller contact patch) = better mpg, but really crappy handling...

higher tire pressure=less rolling resistance (tire doesn't drag)... = better mpg... (just don't overdo it...)

any nice looking set of aftermarket rims and tires will lower your mpg... only way to counter this (partially) is to buy lighter racing rims and use low rolling resistance tires (research their ratings!!!) at the highest recommended safe pressure.


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## zakezuke (Mar 22, 2003)

What i'm more interested in is the effect of tire size as it affects the after final drive ratio. 

I've done no actual research on this issue, but I would imagine that your tire size would have a measurable effect, as well as the other factors of resistance, psi.... etc etc...


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## cargeec 99xe (May 10, 2002)

If you change the diameter of the tire, your speedometer and odometer will be off. I'm pretty sure that's illegal.

Maybe you could get a hold of some 12" alloy rims off an Echo and use some 155 series tires, but at the same diameter as your stockies. Skinnier tires also have less wind resistance.

(Of course, if you want to get better mileage, you could change your crankshaft pulley, install a header, exhaust, remove the ac, advance timing, upgrade the ecu, etc...  )


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## zakezuke (Mar 22, 2003)

I've never actually been told that selecting a tire size is actually illegal. I'm sure diffrent tire/wheel sizes can affect your speedo, but based on what i've observed in court in my state, you can talk your way out of a ticket if it's shown your speedo was off and you had a mechanic fix it. A common explanation in court was, "sorry but I got new tires, and the speedo got thrown off". 

Of your reccomendations
"(Of course, if you want to get better mileage, you could change your crankshaft pulley, install a header, exhaust, remove the ac, advance timing, upgrade the ecu, etc... "

Pully - haven't done that yeat
header - haven't researched that
AC - don't even have that
ECU - haven't researched that yet.

I'm focusing on tires at the moment as it's most likely my next investment. In my book I rank brakes and tires as the highest priority items to keep ship shape based under the assumption that it doesn't matter if your car doesn't move, it does matter if it won't stop.



Besides.. if this were true in my state, then I shouldn't have been able to select a wide range of sizes for my old car, from 165 70 175 70,80, and 185 70,80. Didn't seem to be an issue. My last few sets were purchaced at costco... pretty much grab a tire of your choice and put it in your cart, they put it on without question.


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## bahearn (Jul 15, 2002)

There's no legal issue as long as you aren't negligent.

Taller sidewall over stock = larger diameter = taller gearing = fewer revs per mile, which should give better gas mileage.

It will be tough finding taller tires in a 13 since you're probably already using 75-series tire. You'd want an 80 or 85-series tire in 13".

If you want better gas mileage, get a hybrid or a motorcycle.


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## himilefrontier (Jan 21, 2003)

Probably a 155 80 13.It won't last too long in a FWD application, but it will be better on gas!


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## zakezuke (Mar 22, 2003)

Yes, looks like I have 155 80 on the front. Not sure about the rear though, they are only marked 155 R. 

As far as getting getting a hybrid or motorcycle... not at this stage thanks. While I like the idea of a hybrid to make basic store runs, not within my present budget. Besides... I do consider 35 to be most acceptable for cars, though I had one car in that past that got 40.


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## tkvtec (Apr 20, 2003)

I just went from 175/65 14's to 205/45 16's and My handling is much better, overall diameter is increased by about .25" and gas mileage is about the same even with my harsher driving I've been doing because I know my car can now handle it. P.S. my new 16's weigh about 15.5 lbs a piece which is a good weight reduction over the stock 14" alloys even. If you get larger rims, make sure they weigh less than what you have, that is if mileagfe is important. Definitely do not go with tires of smaller diameter, you mileage will suffer and your speedo will say your going faster than you actually are, which isn't really a bad thing. I could probably use something to help slow me down a bit.


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