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Tires/tyre minus sizing


hello. i own a Subaru forester 2001 imported from the USA. our roads are mostly uphill or downhill and i am not satisfied with the gas mileage.
will replacing the original tires with smaller tires improve gas millage on such roads? thank you.


A car's fuel economy is not much affected by tires - particularly tire size.  However, there have been some experiments that say that larger diameter tires help fuel economy to a minor extent - we're talking percentage points here.  But the problem is that you will lose some pulling power - and that might be important for the hills.

What can affect fuel economy - from a tire's perspective - is careful selection of tires.  

There is a tire technology triangle involving treadwear, traction, and fuel economy.  In order to get good values in one area, the other areas have to be sacrificed.  So you need to select a tire that have the balance you are looking for.

Also, tires labeled "LRR" aren't "Low Rolling Resistance" in the absolute sense - only in the sense that compared to other similar tires #meaning same treadwear and traction properties#, LRR tires have better Rolling Resistance.

What the largest tire that will fit on a 2001 Subaru Forester?  According to Discount Tire, is either 225/60R16 or 225/70R15.  Regardless on what wheel size your car has, there are some tires that will work.  Now all you have to do is figure out what is available in your area and what compromise you are willing to live with.  


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Barry Smith


I have over 30 years experience in the design, manufacturing, and testing of tires. I have served as the technical advisor to the "800" number. I have authored or co-authored many publications - usually without credit. I can answer almost any technical question, but please don`t ask me to compare brands. I probably have prejudices because of my work experience.


Member SAE (Society of Automotive Engineers) Member Tire Society (Tire Technical Organization) SCCA Regional Competiton License holder Authored many training manuals on tires, their care and use.

SAE (Society of Automotive Engineers) SCCA (Sports Car Club of America) Tire Society

You may want to visit my web site:

I am a graduate of the University of Dayton, Dayton, OH - BME, 1971 I attended graduate school at the University of Akron - but did not complete my PhD - something I regret.

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