I cant help you with ice/snow suggestion. Only that I stick with stock diameter to maintain maximum torque and speed. I hear most wheelers will handle 26’s but once past that you may have to jack with clutching to make up the difference in low end performance. You will never get top speed back which to most is no big deal but it is to me.
Suzuki is exactly right. Stick to your stock size or you will be dealing with performance issues without a clutch kit, which can range from $150-300 plus your time to install. Only time I have ever gone up in size is on sport ATV’s, which can be remedied by adjusting the sprockets. You could go a touch wider as long as you ensure it wont rub on anything and your rims can handle them.