Wanting to upgrade size in my tires and wheels.

Im thinking about upgrading my 245/75/16 to a 265/75/17. I have a 2.7L so Im hoping this wont lose much power in my truck. Am I going to be ok?

 

You will be fine on power. The new tire is only 7% taller and has a 7% larger circumference. Bigger rolling stock takes a little extra power to move, and a larger circumference takes more torque to move the same distance with less RPM's but 7% isn't a large increase.
If anything I would be concerned about the taller tires rubbing the fenders when you turn (if you aren't lifted). Depending on how far the new rims stick out (i.e. offset) you may have alittle problem with rubbing.

 

Havnt lifted it yet. Would that really be close to rubbing it? I thought it would take maybe 30's to do that

 

265x75x17 is a 32-5/8" tall tire

 

Here, read this thread: http://www.tacomaworld.com/forum/wheels-tires/67550-largest-tacoma-tire-sizes-stock-suspension.html