Many thanks for all the feedback, everyone.
Seems there isn't enough support for having a tire pump at the SCs.
So I'm with SamT and Morristhecat as the next best solution: Lug around a portable air compressor.
It should take power from the cigarette lighter power socket. Would be nice if it can also be powered by standard 220V HK/UK-type socket (BS 1363) so it can also be used at home to inflate pool/beach inflatables (tubes/toys/loungers/rafts).
I actually researched it a few weeks ago and found these links useful:
Top 10 Portable Air Compressor for Car Reviews
http://www.scribd.com/doc/211884409/Top-10-Portable-Air-Compressor-for-Car-Reviews
Top Portable Air Compressor for Car Tires Reviews 2014 My Recommendation ~ My Home and Kitchen Love
http://jimmyputih3.blogspot.hk/2014/01/top-portable-air-compressor-for-car.html
Top 10 Best Portable Air Compressor for Car Reviews - YouTube
https://www.youtube.com/watch?v=yVw2SlA-Gt4
These seem to be the top make/models:
#1 VIAIR 85P Portable Air Compressor B0036E9VB6
• It is really fast, quiet, and the build quality is very impressive.
• able to be powered by a cigarette lighter power socket
• almost twice as fast as the 70P and every bit as quiet
• No air loss
• Not heavy
#2 Viair 00073 70P Heavy Duty Portable Compressor B0012WHBSO
• Great quality
•Compact size
•Very quiet air compressor
•Fast and reliable
•Nice carrying bag available
•Ideal road side emergency kit
•powerful enough to inflate even sport tires
•super fast
•built quality is very good
•inflates other stuff (beach toys, sport equipment)
#3 Viair 00088 88P Portable Air Compressor B005ASY23I
• Very well built and quiet air compressor.
• Long enough power cord and hose easily connect to the rear tires.
• Best choice 88P portable air compressor.
• A must have for long distance travel.
• Minimum cool down time (approximately 5.5 minutes)
• Fills up to 33" tires.
• 20 ft. maximum reach.
I wonder if I can get the VIAIR 85P Portable Air Compressor B0036E9VB6 (or similar) in Hong Kong.
How about a group buy for HK Tesla owners?