WILL XXR 530 RIM w/ 33MM OFFSET FIT RX8?

I currently have plus sized 245-40-18s on aftermarket OEM rims. Looking to buy XXR 530 18-8.75 inch rims which I am told by XXR and research have an offset of 33MM. If I keep the current tires will these rims fit or will I have to go back to stock 225 /45-18 tires? (Conti Extreme Contact DWS). These have a pretty deep concave to them and was told by XXR they should fit without fender rolling. Or should I scratch these rims altogether? Do not want to do any fender modification just to get a rim on. Thanks!