Valve Stem

[byker]

I will be replacing valves stems (wheels) on my 87K100rs but having a hard time determining the correct size. Does anyone know the correct size?

[PGlaves]

Here is what I wrote in my August 2007 Benchwrenching column:

"BMW designates them as 15mm valve stems. In this case that is the diameter of the portion of the stem that seats in the hole in the wheel. The hole in the wheel is smaller, of course. If you go to an auto parts store you will find stems generally available in two sizes: to fit a .453 inch (11.5mm) hole or a .625” (15.9mm) hole. The stems I bought which were designated to fit a .453 inch hole measure .59 inch, as do the “15mm” BMW stems purchased at my dealer (.59 inch is equal to 14.98mm).