I checked around and 190x50 tires are a very odd size. We are not able to source either 190x50 tires or tubes right now. Since 190x50 tubes are not currently available I would use a 200x50 tube as it is the closest size available. We sell 200x50 tubes on This Page. We can check and see if there are any electric scooter repair shops in your area. What is your zip code?