Seriously? New tires. I'm sure everyone else has said the same thing. Hang on to that Accord!
Also, if you REALLY want to give up $400 a month for the next 5 years... put that money into savings for the next car. That way you can buy it outright when the Accord finally does need to be replaced.
This is a really good point! If you have the money for a new car payment, start a "car" category in your budget. There might be months that money goes to new tires, etc. but in general it will make the cash buy a possibility when the time comes!