ThanksJayson said:The stock wheels are 8" wide, and 9.5" wide not 8.5 in the front. So if you go with a 8.5" wide wheel you can run the a 245 or a 10mmwider 255 wide tire.
So if you want to keep the stock widths yes 245 and 275 is fine. If you want to upgrade the front a bit go 255 and 275.
The midle number is the sidewall height and it is the apect ratio to the width. So the smaller that gets w/o increasing the width the smaller the sidewall is. It's normal to run less sidewall as the wheel gets so yes you can run what you think is right as it is right. Or you could run a 245-40-19 and 275-35-19 which would give you the extra sidewall like the stockers have. Hope this helps.