You can... but should you? Most reputable tire dealers will only use factory reccommended sizes. That can be expensive. I have the M35s and had to buy "Z" rated 19" tires... almost $1600!!! Now, I drive the car hard and love the new tires. I could have put a less expensive tire on in the same size but would only have saved $100 and not had the handling capability. It just wasn't worth the small difference. All that said; If someone buys a luxury car and can't afford the gas, tires or proper maintanience then they probably should buy something less expensive that they can afford to maintain properly. I am not familiar with what tire size goes on the "X" model but I do think they will be less expensive than mine. Good Luck.
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