Originally Posted by MAST4R

There are exactly zero reasons other than looks to have a 20" tire on a 4R. Theoretically, on a sports car, you will get better cornering and handling with a bigger wheel and a shorter sidewall.

Of course, the taller sidewall will improve ride quality. Probably by quite a bit. I suppose 17" tires are also cheaper and there is certainly much more choice to be had.

As with all tire companies, Cooper has all sorts of tires. Mine are heavy duty desert tires and are great (made by Cooper who own the MT brand). It is a fairly major brand. All brands have some tires that are better than others. I have no idea about the specific Cooper tire you mention.