2008 sts4 20in rim questions
 

i want to put a set of 20 on my 08 sts4 and was just wanting to no if the information i have is correct
bolt pattern 5-115
tire size my car now has front and rear tires that r the same size witch r 235-50-17 from factory but places like tire rack tell me that i need to do 245-30-20 front and 255-30-20 rear or should i do the same size front and back tires???
also if i were to find a used set what r some common cars that use this same bolt pattern
thanks

There are some other cars like this which have the same bolt pattern and you can get it from the eBay and other automotive stores which on high standard. CTS have also the same pattern i think.