Can I increase front wheels to a 18by 9.5and back wheels to a 19by 12 on a base c6 ,buying new wheels ,offset on front is 56mm and back is 40mm ....thanks for any help...will also be buying coilovers if any body has input

 

Welcome to the forum. You could try checking with Tire Rack and other wheel manufacturers to see if their database can answer your question. Expect some of them can. But you do need to add the year and model to get an answer.