I need to replace the wheels on my 2006 STS V8 AWD. Currently the wheels are 235/50R18 on the front and 255/45ZR18 on the rear. I am having a heck of a time finding replacement wheels with the rims wider in the rear. The local tire guy told me he could find 4 new rims all the same and recommended that I go with the 235/50R18 all the way around. I'm worried about different wheels/tires on the rear screwing up the AWD gearing. Can anybody tell me if its ok to go with the same tires and rims all the way around? Please forgive me if this question has previously been asked but I couldn't find anything on it in the forum. Thanks for any help.