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2010 Outback, 2.5i Premium
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Hi All - I used to have a 2008 Outback and purchased new tires for it about 10K miles before I traded it in for a 2010 outback. Prior to trading it in, I pulled the tires because they were basically brand new and i figured I could just switch out those tires when the new ones wear out. Well, it is about that time now, and I noticed that the 08 took 225/55/17 and the 2010 takes 225/60/17. I went to Sam's to have them switch out the tires and they mentioned that not only couldn't they do it (policy against downsizing tires size), they don't recommend it because it could throw a lot of the calibrated systems off.

Looking for some input to see what the implications are of going to a smaller tire.

Thanks!
 

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2012 4LT Centennial Edition Grand Sport Corvette convertible
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496 Posts
The implications (risks) are pretty simple - your speedometer will be off by approximately 3.2%. The math for the tires indicates the 225/55/17s are 26.744" in diameter and the 225/60/17 are 27.630" in diameter. Roughly speaking, this means that, at an indicated 60 mph on the speedometer, you will actually be going 58 mph. Nothing else should be affected.

Other than that, you will physically have less ground clearance. Take the car somewhere else and have them change them over if that's what you want to do.
 

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2004 Outback Wagon, 2.5, 4EAT, All weather package.
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1,040 Posts
The biggest reason they do that is because of huge liability, and the sue-happy society we live in. If they install the wrong tires on your car, you lose control of the vehicle and cause an accident, they will go after Sam's for damages.

Please note the load indexes on the tires as well. It is a very, very poor idea to under rate the tires on your vehicle. Do not go under the minimum load capacity required by the manufacturer, found on the door placard on the vehicle.
 

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2013 Legacy Lim CVT Car: 2011 OB Prem 6MT Car: 2006 Miata GT 6MT mc: 2003 Honda GL1800A * Reunite Gondwanaland *
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3,567 Posts
The implications (risks) are pretty simple - your speedometer will be off by approximately 3.2%.
Unless (like mine) your speedo is already 2%-3% optimistic -- in which case
the smaller diameter tire would boost the speedo error to 5%-6%. OTOH, if
you fly-by-Garmin, the speedo doesn't matter.

...YmphMV,

Looby
 

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2012 4LT Centennial Edition Grand Sport Corvette convertible
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Unless (like mine) your speedo is already 2%-3% optimistic

Looby
I've checked my speedometer with a GPS and it's pretty much dead-on.
 
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