You only specify front wheel and tyre size as 8.5 inch, 235-45-17 for a 1989 BMW Alpina E32Whereas the rear wheels are 10 inch!So getting information from your website is non existent
The wheels on my 1989 Alpina B11 E32 are 8.5 on front and like 10" on back!
None of your details mention the size of tire meant to be on the 10" wheels!
...not sure on what’s the best / biggest / widest / maximum tires or rims will fit your car?
Write about the tires you are currently driving on.