Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Buy tires and keep car for 12-36 months, or replace car now? 
I don't see how anyone could give you a hard-and-fast formula, unless they know where to get some applicable statistics. Because several factors here are not a straight calculation. If you don't replace the tires but keeping driving the car, what is the increased probability that you will get into an accident because of the bald tires? How much will bald tires vs new tires affect the selling price of the car? Presumably the longer you drive the car after getting new tires, the less increase this will give to the market value of the car. What's the formula for that? If you keep the car, what's the probability that it will have other maintenance problems? Etc. That said, it's almost always cheaper to keep your current car than to buy a new one. Even if you have maintenance problems, it would have to be a huge problem to cost more than buying a new car. Suppose you buy a $25,000 car with ... what's a typical new car loan these days? maybe 5 years at 5%? So your payments would be about $470 per month. If you compare spending $1000 for new tires versus paying $470 per month on a new car loan, the tires are cheaper within 3 months. The principle is the same if you buy with cash. To justify buying a new car you have to factor in the value of the pleasure you get from a new car, the peace of mind from having something more reliable, etc, mostly intangibles.