I have an 2006 Porsche Cayenne and I am needing to put my first set of tires on it. I don't want to void my warranty for not using the correct tires. My tires size is 235/65R/17 with a PSI of 38 in the front and 49 in the rear. I was told I need to have a 108V tire with a N designation. I emailed Michelin and they said they didn't have a tire. Can someone help me out please. Thanks in advance for your help!