Truing-

You need to true your wheels when there is enough wobble in them that it becomes noticable, either feeling it or seeing it. A lot of folks wait until the wheel begins to rub the brake pad.

If you have a treaded tire, you would want to replace it no later than when the tread is almost worn away. Some tires have some type of wear indicator and some just have cords. If you do not ride often, you might want to look for cracks or splits in the rubber. If you notice any kind of strange bulge in the tire, replace it right away.

Muaythaibike said:

2 basic question on wheels.

How can I tell when my wheels need truing?

Also how can I tell when my tires need to be changed?

Basically, if it is wobbling (by more than a few mm) then, you will need to true it.

Scotty

To me one millimetre runout is too much.
It could be indicating spokes loosening and it is a lot easier to true a wheel if you don't let it get worse.
It is often a case of only one or two spokes that need tweaking.