Bike tyre size question...?

Question

at the moment i am using a 700 x 25c tire on my road bike, what do those numbers mean and can i use different sizes with my wheel/rim if u get me

Answer 1

700 is the size corresponding to your wheel diameter.  You can only fit 700c tyres onto your wheel.  25 is the width of the tyre in mm.  You can fit other sizes within reason.  Wider will increase drag but give you a bit more of a comfy ride.  Narrower will reduce drag, but - assuming you pump them up hard - feel like riding on solid rubber.

Answer 2

700millimetres x 25millimetres

(radius)...............(width)

i don't think you can, 25 mill, is usually max for a racer...<^><...