The stock size is 225/55-16. I had 245/50-16s on mine for a while but it was pretty clear by looking at them that they were too wide for the 7" wide rim. The next set of tires I bought I went back to the 225s and saw no loss of performance. With the "proper" size tire the footprint is optimized - with the 245s you're really not going to get the full benefit of the fatter tire because the wheel isn't wide enough to support it.
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