Well got a huge chunck of metal stuck in my tire gogin through a soncrution area by my work.... so now i need to get a new one and the dealer quotes me 230 bucks, and itll be a week to deliver it...fun part is they wont order it until i pay which i don't have an extra 230 bucks atm....so im stuck with the spare.....how long will that thing last if i keep it under the recommended 50 mph?