If they are standard offset wheels I think the conclusion is 225 65 17. Many threads cover this. I am about to fit the above so hope they work!! Clearance to strut spring cup is the issue. Also, at the front the strut arm to track rod end.
The largest practical tyre diameter is 28.6" in diameter, on a 225 section. This will fit on the standard wheel, and "just" fit the suspension/ body.
A 225/70/17 is going to be around 29.4" in diameter, so well above the maximum standard size.
Going larger than 225/65/17 will require a suspension lift, hub spacers and possibly trimming of the arches too. The speedometer is also calibrated for a 28.6" tyre, so going larger will make that inaccurate, and could well affect the acceleration of the vehicle.