I would like an answer for this, also, if you find out/have to figure out out yourself. I'm also wondering if you will need to add i3s wheel flares to keep your fenders from being destroyed by flying road debris. As well as whether or not the larger footprint of the tire will keep the rear...
I go 70+ mph on the Rex on flat pavement. If it's been coded to turn the Rex on manually, you can do so once the battery is down to about 70% and see how well the Rex keeps it charged. You'll get it home no matter what, though.
I wish I had gotten every option they made for mine. The tech package (and rex) was a deal breaker for me, also. The screen is way better. I also like the adaptive cruise. HK audio system would be nice, as would a rear camera (even though it's a small car, the belt line is pretty high). My...