None whatsoever. The large local dealer from whom I bought the vehicle is selling 17" wheel/winter tire combos for the PHEV, and has had no problems at all with them. Mine are not the steel wheels that he sells, as I was looking for a permanent switch to smaller wheels/larger tires for additional ground clearance, which I tested to the limits yesterday, and I'm very pleased with the results. The new Axion alloys and taller tires (more sidewall) look great on the car, but I'm unable to post pics, as this forum doesn't seem to like my cellphone .jpegs . The new tires are 235/65R17 Yokohama Geolander G015 AT, which are both all terrain, and all weather snowflake symbol rated, so I don't have to change them twice a year. I bought a 5th tire/wheel as well, to carry as a spare. It will be included in each 8000km tire rotation, so the whole set should last 20% longer too.
I don't think there is any additional hardware mounted at the wheels for regen. braking, I believe it is all software controlled through the motors. Kal Tire mounted them and checked for clearance of all items during full steering and suspension travel, they have a fancy lift with hydraulic jacks to test all that.