A good set of all-season tires keeps you planted on wet highway off-ramps and cuts down on winter sliding without the swap hassle. Keeping them fresh is just part of running a car, but four new corners usually run about $800 once you add mounting, balancing, and disposal fees. May tire safety promotional events are one of the best times to buy because manufacturers drop rebates and shops compete for your business before the summer road trip rush.
You should always negotiate the out-the-door price of the rubber and installation before you ever talk about how you are paying for it. A financing window is just a tool to spread out the cash flow for the deposit and the extras, not a blank check to ignore the bottom line. Getting quotes from a few local shops and big-box clubs will keep the price soft before you lock in your payment plan.
Remember that the 0% intro window is a strict deadline, not free money, and any remaining balance left over when those 18 months run out will get hit with standard interest charges.