snow tires

Worn one season on Ford F150 XLT. I now have a Ford Lightning Flash with 20" tires. $1,400 includes OEM Cast Aluminum Rims. Half price of original cost.

I have an extended range Lariat. This is my first ever truck. Winter is emerging here in Central New York and I feel I should get snow tires. Is there any reason I shouldn't just order some Blizzaks and have my usual mechanic install them on my existing rims? Since this is my first truck I...