I just won an auction for a set of Kumho Ectasa 711s that are size 225 40 18 all around. I am wondering if these are suitable for 18 X 8 rims (M5 replicas) on an e34 540/6. I know that the recomended size is 235 40 18 but are these good enough? Will I notice any difference? Anybody have experience with these tires? Any input is appreciated. Thanks.