That's plus sizing you are talking about, its done to improve the performance/ handling of vehicle and not the ground clearance.
Raising a vehicle is not only bad practice, it's also dangerous. You're raising the centre of gravity, which makes the car unstable at speed, more vulnerable if driven in cross winds or bad roads with negative camber. A sudden change of direction (like swerving to avoid an obstacle) could cause the car to over turn.
The suspension of an automobile is a safety-related aspect, the ride height is set buy the manufacturers, based upon extensive testing, involving several hundreds of hours of R&, and millions of $$$. Do you honestly feel you can better the factory settings, by raising the height artificially?
However if you still want to do it Pls check out the links;
Tyre Size Calculator - Legal Requirements - Etyres
Plus One Tyre Sizing: Learn How To Plus Size Tyres & Wheels