My Toyo TQ DR's reduced my effective gear ratio down to 3.40

Since the 18" TQ's are approximately 1" larger in diameter, it rolls 34 revolutions per mile less than the stock diameter. I would need at least a 3.70 gear set to get back to an effective 3.55 gear ratio. I changed the Rev's per mile in the tune to keep the odometer honest. The car actually feels better. The instant hit of 500 ft lbs of torque is a little less harsh on the tires and traction has improved greatly. 

Tire Size Change, New Gear Ratio Calculator

www.4lo.com/calc/geartire.php