Bicycle Mechanics - rotating tires

I'm fairly new to road cycling so this may be a dumb question.... Do I need to ever rotate the tires on my bike? Either turn them around or switch front/back? Also, how do you know when a road tire needs to be replaced? Thanks in advance...

Tires need to be replaced if the threads in the casing get cut, or before the tread wears down to the casing. If the wear on the tread is uneven you also need to check for something out of adjustment in the wheel or brakes.

The tire direction of rotation is supposed to be with the arrow pattern in the tread pointing forward at the top of the tire. The tread on a road tire is really for decorative purposes only, so this isnt important.

You always want to have your best tire on the front, to maintain control in case of a blow-out. Some people put their front tire to the back when the back wears out and put the new tire on the front. Back tires wear faster than the fronts because of the extra weight on them and the driving force.

Here's the same topic discussed at road bike forum.

http://64.191.20.129/showthread.php?t=58931&highlight=Rotation

I tend to agree with AndrewP about the tread direction. I used to have slick tire which have no direction, made no difference. I install the tires where the brand name shows on the power train side, it's only because all the bikes in the catalogs are shown that way and it makes me feel good doing the same way.

Legally and majority wise I agree with Andrew on the subject of the best tire being on the front; but (you had to know this was coming!), for the last 25 years I have always put my best tire on the back. why you scream? Because when I first started racing all the guys said put your best tire on the front incase of a blow out you would have an easier time with a rear blow out. While this is true (especially back in those days when I rode on tubulars), the problem is that if you put your worse tire on the rear your always getting flats back there because your tread is thinner and you usually manuever around an object with the front but the rear hits it anyway or the front hits and sets it up to strike the rear! So I (probably incorrectly) rationlized that by putting the best tire on the back my flats would be greatly reduced, and that is true; doing this saved me from losing races back when I use to race. I have had sudden blowouts on the front and rear with both tubulars and clinchers and the only time I ever lost it was when a rear blew going around a sharp corner and the backend washed out from under me-similar to a car experiencing massive oversteer.

So yes I do rotate the tires sort-of; let me explain (my current tires last about 2800 miles on the rear and 3700 miles on the front if just left alone), lets assume I buy a new set of tires; I usually run the tires untill they have about 1800 miles then put the rear to the front and slap a new one on the rear; by the time the rear is ready for the move up front the front tire is ready to toss. Of course all tires wear at different rates so you have to experiment. And if you want to subscribe to the "right and legal way" then just reverse the rotation with a new one going on the front.

And you can tell when the tires are getting low because they will look squarish or flat on the tread rather than round. You can also take the tire off and check the thickness of the rubber compared to a new tire of same brand and model.

My tires rotate when I pedal...!

But otherwise, no, I don't rotate them. I simply replace them when they are worn out, which means I use 2-3 rear tires for each front one.

Just to make things more complex, I do change the tires when Winter comes: I use knobbies for better traction in the snow and slicks the 8 other months.