In the past, several of my biker friends have suggested that regardless of miles, tires that are 6 years old or older should be replaced. My 09 Burgie (bought in 2010) will be approaching that milestone. What is the general concensus? Should I replace the soon to be 6 year old tires? Oh and it's the original battery also. Is there a new battery in my not to distant future as well? Snow makes me think of maintenance. Thanks in advance for your thoughts.