I believe these sizes are for 7 series, but will they fit on our E60s?

Since they are thicker than the OEM size, does that mean the wheel gap will look smaller?

front tire's are 245/45R19 with 19X9 rim
and 275/40R19 in the rear's with 19X10 rim

 

recommended sidewalls for 19" wheels would be 35/30, and Id recommend sticking to that. for those dimensions of wheels, we usually pair them up with sizes 245/35/19 and 285/30/19 .

 

These will definitely rub.
I have 255/40 and 285/35, and its a close call for non M5 with seven series offsets.

Also, there is no point going with narrower tires, because 245 on 9" and 275 on 10" wheels and low profile looks a little too "german look" (stretched). M5 has the same sizes as mine, but the wheels are 8,5" and 9,5" ET is different also Front have 12 and rear 28. I have ET24 for both.

The gap is fine now, dont need thicker sidewalls (comfort and handling is optimal with these):