Just recently purchased a 06 Base XType with 40000 miles. The tires look a bit worn and I plan on replacing them. I assume they are the original tires as the car doesnt have that many miles on it. They are Michelin Pilot MXM4 235/50 17"
This doesn't look to be a standard size? When I look for tires on the internet, this the size is not listed under standard size. When I replace them, should I look to go back to the original size or is it ok to keep this size?

 

Not original.

17" on an X-Type should be 225/45R17 or 205/50R17, your speedometer must be a mile out....

 

Ron, as long as the tires are not rubbing during normal use, you can use that size tire. Yes, it will throw off your speedo a little bit, but not that significant. The bigger thing will be the additional cost of keeping that non-stock tire size. What you will find is that there will be fewer tires to choose from. For example, the 235/50R17 has 41 options, the 235/45R17 have 103 options, and the stock 225/45R17 have 166 options. You will probably find that the 235/50R17's will also be a fair bit more expensive. So, up to you.