[mjl1023]

I recently had to replace the four tires on my 2008 Outback due to having a screw near the sidewall. I replaced the four originals (225/55/17) with four 225/50/17's. The shop which I went to was the only shop open on a Sunday and that was the only closest size available. Will going from the 55's to 50's make much of a difference or does it even matter that much??

 

[beachedwhale42]

First off, welcome to the forum!

The 50s will be a bit smaller in diameter and circumference. There are many online calculators, or you can always look up the tire on Tire Rack to find specifics, but looking at the first tire I could find available in both (Blizzak WS-70), the diameter of the 50s is .9" smaller.

You'll lose roughly half an inch of ground clearance (if the diameter delta is .9", the radius delta will be .45", thus losing .45" clearance), but the car will be lower with lower profile tires (typically better for handling). Also note that the max load weight might be a bit lower, and your speedometer might be a tad off. I wish I could tell you if it will read faster or slower than reality, but I can never keep that straight lol.

Bottom line, your car will be roughly half an inch lower, but probably perform a tad better. You probably won't notice much unless you need the clearance for off-roading or snow.

 

[1 Lucky Texan]

faster than 'reality', and rack up odo miles 'faster' than reality.

you could check it with a GPS to know how much correction to figure. probably a few percent.

 

[plain OM]

The Miata tire calculator is great for this: Tire size calculator.

The lower profile tire will turn more revs per mile than the original tire (780 versus 754), and cause the speedometer, and odometer, to read higher by 3%; you won't be going as fast as the speedo indicates, if it was right-on previously.

 

[oldandnotintheway]

On my 2011 Outback wagon, 2.5 L, the original tires were 225/60/R17. For the last two winters i have used studded tires 225/60/R16, and have not noticed any problems. But i recently learned that it would have been better to buy 215/70/R16 winter tires. What type of problems might occur if i keep using the 225/60/R16 winter tires?

 

[AWDFTW]

None.

 

[DrCloud]

None.

Well, right, if he put those 16s on 16" wheels. If he stretched them onto the 17" wheels, though... HPH