The different tyres make a HUGE difference to your traction!
and in snow levels they are vital.
I like to buy the speed increase and the 1st tyre upgrade fairly soon. This gives you a good competitive edge in the first few races so you can build some more cash.
The fifth gear gives you a much higher top speed and should also be high on you list of priority items.
...Thats all I can remember right now ...sorry
