Last year I bought a 70s Japcrap Jazz Bass from Oxfam for £50, it's great but I need to get around to replacing the electronics.

Point is: fun as it is to play, I'm no fan of the floppy strings. Soooooo, does anyone know what guage strings I would need to use on a 30" scale bass to get the equivalent tension of a standard guage (45-105) set of strings on a 34" scale bass? Hex-core, nickel-plated roundwounds, of course.

Ken Smith Short-Scale strings are .44 to .106, and they seem to work well for the Gibson EB-3 (32" scale). I don't know if they would works as well for a 30" scale bass, though.
"Maybe this world is another planet's hell?" - Aldous Huxley
I'm not sure that would do it, medium guage on a short scale is still floppy.

So I found the D'addario tension charts:

Long scale:
Item #	Note	Inches	mm	lbs	kg
XLB050	G	0.0500	1.2700	50.300	22.810
XLB070	D	0.0700	1.7780	55.610	25.220
XLB085	A	0.0850	2.1590	45.340	20.570
XLB105	E	0.1050	2.6670	38.080	17.270

Short scale:
Note	Inches	mm	lbs	kg
G	0.0500	1.2700	39.160	17.760
D	0.0700	1.7800	43.300	19.640
A	0.0850	2.1600	35.300	16.010
E	0.1050	2.6700	29.650	13.450

So for 4-5kg of tension is lost due to the change of scale. Going up to a 55-110 adds enough tension for the D G and A strings, definitely, but the E string is is still 3-4kg short. Maybe a light guage B string would have to do?
I'm really interested on how this sorts out for you Jon. I love my little short scale Fender but the string tension is bothersome, esp. in the E and A. I wish I could figure out what strings are on my Brice 6 string, because they are just perfect.
Maybe I'll just have to get some steel flats for it? I can't find a short scale set above 105 and while I'm happy to rewind the end of a used set of strings I'd rather not risk unravelling a brand new set.
You could always turn it into a Piccolo bass. Perhaps that would work? You would certainly have plenty of string tension.
"Maybe this world is another planet's hell?" - Aldous Huxley
Quote by Spaz91
Well I'm hoping to use it for a Rush-themed recital in a few months, I'm not sure that octave will go down well with my bass tutor.

No problem. Stick to early Rush tunes, and use the Piccolo bass to play Geddy's vocal parts. That should work.
"Maybe this world is another planet's hell?" - Aldous Huxley