Type 'D' front engine buses tend to be like a cow on ice when the roads get slick. With the engine and most of the transmission in front of the front axle the weight bias towards the front tends to overload the front axle and barely loads the drive axle. You end up with a vehicle that doesn't get good traction and the bus tends to oversteer--a little input does a lot.
Type 'D' rear engine buses have great traction but tend to understeer when they are on slick roads--you put steering input in and nothing happens so you turn the wheel a little more and then all of a sudden it grabs and then you are going way to far.
Type 'C' buses are usually pretty mannerly when driving on slick roads. There are some that have a driven front axle. Those buses tend to go just about anywhere you want them to go and are able to drive back without any assistance. International 1997 AMTRAN
Most western states and provinces require you to carry traction chains from Nov 1 to March 30 every year. The lack thereof not only may sideline you until the roads clear but it could end up you getting fine of $750.00.
There are virtually no roads in the US or Canada that a school bus doesn't travel down twice a day. If you understand the limitations you can get a bus you own down those same roads without any problems.