Hello all,

Even with my first Mitsubishi, a 1976 Dodge Colt(rwd), I have used a larger diameter tire.
It is not as big an issue as most people claim.
Other than clearance issues(rubbing, etc.) and weight, which are true issues, the motor and transmission only sees 1/2 of the increase in new tire diameter. It only sees, feels, or literally has to push the increase that is measured from the center of the hub to the pavement. That distance, or measurement, is further reduced because of the squished/flexed sidewall of the tire.
Mount the tire on the wheel, and before you mount it on the car, measure from the center of the wheel to the ground. That measurement would/should be truly one half it's full height, it's true radius. Once you mount that on the car, the weight of the car pushes down on the tire, flexing the sidewalls, ultimately reducing(by a small amount) the radius of the tire.
So the engine/transmission see/push the slightly reduced radius of the new larger tire.