Four-way tool helps remove valve cores. Compatible for all vehicle valves as well as air conditioning units. Retaps threads inside and outside. Four tools in one. Reams inside valve.
This worked for me after breaking the valve core tool on the end of the slime bottle cap. I bought this valve core tool and it did the job. It's a bit fiddly to unscrew the valve cores from my bike because the crosses are a bit long to twist between the spokes, but if you bend the valve stem a little you can make a full turn and unscrew the valve core.
Pros
Compatible with all car valves as well as air conditioning