Heading from Ontario to Vancouver Island for the Winter

I can't speak for the route from Ontario as far as Alberta, but I would recommend the route through Edmonton and follow the Yellowhead highway west through Jasper then down through Kamloops. From Kamloops follow the Trans Canada to Vancouver. The route through southern B. C. can be done without major passes, but there is some quite slow winding highway. Following the Trans-Canada is an option. The pass over the B. C./Alberta border is not real high going west, but there is a long down hill into Revelstoke. Roger's Pass in B. C. is the major pass but this is the route that most people use, including the commercial trucks. Snow is possible any time after Sept.(there is snow on the mountains this morning) but the later you get after mid-Oct, the greater the chance. You can check the Drive B. C. highway cameras if you have internet access as you travel to see if there is snow ahead. Another risk when you travel late in the year is an early cold snap which could freeze RV water lines. A few years ago many RV'ers were caught in early Oct. with sub-zero temps and many had to replace hot water tanks etc. Snow tires are a very good idea, but unless there has been significant snow, it is unlikely they will be checking to see if you have them. I have never seen a snow tire check in almost fifty years of living in B. C.