Hi. I'm in Japan, and I have a 13-year old Bridgestone Grandtech folding bike. The rear tire won't hold air, so I intend to replace the inner tube. The rims are marked ARAYA 20 x 1.5 GP-710, and the tires say Bridgestone iRC 20 x 1.75. I'll attach a photo showing the valve stem. I'm new to this, and I need advice. I just read that there are different types of valve stems. What type of inner tube should I buy so it fits the rims and valve hole? I plan to order online, so exact specs would be a great help. Thanks.