Anyone know where you can get 650B tubes with long stems?

Hey all,

I'm looking for 650b tubes for my emergency saddle bag kit (I run tubeless wheels/tires). 

I'm running Boyd Joccassee wheels. 

So far the longest presta valves I've found in a 650b tube is 48mm.   These work ok, but there is *just* barely enough valve exposed to get my thread on emergency frame pump on there.   

I'd rather not run valve extenders if I can help it.

Any ideas?

Not sure how wide your tires are, but these should work for an emergency situation: https://www.niagaracycle.com/categories/continental-650-x-18-25mm-60mm-presta-valve-tube?utm_source=TPA%20On%20Google%20Shopping&utm_campaign=Top%20Placement%20Ads%C2%AE%20(SPLA)&utm_medium=cpc&utm_term=People%20Searching%20For%20Bike%20Parts&utm_content=Google%20Shopping&product_id=51139&device=c&loc_physical_ms=9028727&gclid=Cj0KCQiAhrbTBRCFARIsACY7MW0DfotcEkciOJcIBwvtYQZaTpqG_s7f5J27Zk2HrcZKDJi8HWabzc4aAkP9EALw_wcB

I'm seeing tubes with 60mm valves.  Do the Google.
 

Sure, plenty of 650c for skinnies. Not recommended to use road width tubes if you're rolling bigger tires, even if it's just for emergencies. Kenda and Michelin have some 650b for mtb sizes with longer valves... But what's the problem with valve extenders on properly sized spare tube? I must be doing it wrong all these years. Get a tube with a removable valve core and an extender that accepts the core on the top and you're set. If it leaks then reinstall it with a little strip of plumbers tape on the threads... Done.