Anyone know the maximum tire diameter we can mount on an 06 Outback XT?

 

This would be to increase the effective final drive ratio to get better than the 24MPG with the auto?

 

Thanks

as much or more important is the width. get a size skinnier tire. you can always go up or down a size or two. go one size thinner and look at the tread. the rubber compound can make a difference as well. i'm guessing sticky performance tires don't do as well as hard rubber/high mileage tires, but that's just a guess i'm not a tire material expert by any means. these won't be performance tires, but i'm doubting you're auto crossing or anything. skinnier is better in snow/rain too, another plus.

 

if you get much larger diameter you're speedometer/odometer won't be accurate. thinner might give you what you want without the speedo discrepancy. you won't get more than a 1-3 mpg bump in my experience. if you drive alot maybe that's worth it to you.