I have a 2008 Mini Cooper S. A while back, I replaced the tire valve stem caps with metal ones that had a Mini logo on them. After moving from Florida into an area with snowy winters, I'm regretting that decision. My caps are all stuck due to oxidation. I've been trying to break them loose by spraying with PB Blaster but they won't budge. I actually ended up breaking one of them right at the cap. After running to a repair shop down the road just as they were closing, I was told that they could replace the tire valve stems without TPMS for fairly cheap but I would always have the low tire pressure indicator on inside the car. I've found TPMS tire pressure valve stems for under $20 each at www.minimania.com. But, it says that you have to get the sensors as well which are $100 each. My question is, if I get just the tire stem valves and have them installed, will they work with the sensor that is already there? If not, I think I'll just deal with the tire pressure indicator remaining on inside the car until the tires need to be replaced.

 

http://www.tpmssource.com/ cheapest ones I found

 

these guys sell OE Beru TPMS sensors for the 2008 Mini Cooper S for pretty cheap: $60.50 per sensor. They even include the necessary Beru valve with the sensor. You can buy the Beru valve separately too

Mini COOPER 2007-2009 (433MHz) TPMS Sensor Beru RDE008 OE Part # 36236781847 - TPMS Direct for all of your TPMS needs!

TPMS Tire Pressure Monitoring System replacement accessories, TPMS Valve Stem - TPMS Direct for all of your TPMS needs!

 

I'd replace the entire sensor, including the valve. There could be a change that you might have damaged your sensors