26s are pretty huge. You will definitely notice a difference in mileage, performance, and braking effectiveness. I only have 24" wheels on mine, and the stopping distance has increased and brake pads are getting replaced about every 10K-12K miles. I'm upgrading from the stock 12" rotors to 14" and 4 piston calipers to help. I've done some mods just to try and gain back what I lost in fuel economy, which was roughly about 2mpg. Luckily I have 3.73 gears, which helps to get the 360 lbs worth of wheels moving from a stop.:crazy:
I like the big wheel look on SUVs, but too big (like 27" and up) makes it a bit "cartoonish".