Yes, while it may confuse the traction control, fronts will work on the rear and as the 3 lug wheel/tire combination can be hard to find many of us do that on road trips.Just temporarily. Thinking of keeping one in the car as a spare tire on long trips? Is there a permanent location it could be mounted to?
Front and rear not the same 15 inch diameter?
155/60 front is 22.32 inches. 175/55 rear is 22.58. 1/4 inch difference in diameter and 1/8 inch difference on the road or about 1 percent. Can't imagine that would be an issue. That's less than the difference between a new tire and a half worn one.