I am confused about what type of replacement tires I should get. I have not been riding long enough to know the difference between one flavor or another. I have a 2008 with 5700 miles on it and the front tire is about gone. Come to find out I have been riding with 20 lbs. in the front and about 25 lbs. in the rear. I have not developed the good habbit of checking the tire pressure. The tires appeared to be fully inflated and no obvious bulge like a car tire. Live and learn I guess; but I need to know what will be best. I bought the bike new out of the crate in 2010 so the tires are 4 - 5 years old if that makes a difference. I am running on Metzler Z6-G 120/70ZR17 front and Z6 RT 180/55ZR17 "C" rear, any advice on the tires. The rear has more tread than the front, but I think I might just change them both and start fresh. Asside from the obvious expensive lesson on tire pressure, are the valve stems with the monitors in them dependable and worth the investment. I would hate to develop a new good habbit of checking the gauge...and it be wrong. Please advise.