I am new to the site and thanks in advance for the wealth of info I have already found here! I am wondering if I can get away with taller tires than the stock 215 60R 16's that come stock on my 05 Forester. I know I would take a hit on gas mileage but I travel some nasty dirt roads here in the wilds of New Mexico and I could use a beeefier tire if it doesn't cause gearing or clearance problems. Any ideas?

I'd say take her into a tire shop (one you like, or trust, or a good one.) And find out how tall a tire will fit in there.. maybe go a little thiner to help clear your fender wells.. like a 190/195 .. will also help you go through mud better... Maybe like a 190/75 or 80.. bigger might fit.. but it wouldn't hurt to have a tire shop take a couple measurements to see how tall you can go.. Let us know!

Surely a higher tyre will fit fine. Just DO NOT fit a wider tyre, that will mess the handling up.

 

A larger tyre will lengthen your gearing, meaning less torque output at the wheels for a given engine speed. Your speedo will also read lower. Stay within 5-10% diameter and you'll be fine.

This won't answer your specific question about your car and fitment, but it will help you calculate how much bigger a proposed tire is, and how much your speedo and odo will be off:

 

New version:

http://www.miata.net/garage/tirecalc.html

 

Old version (try if the first one doesn't work):

http://www.miata.net/garage/tirecalcold.html

 

Steve