Air Compressors and Spare Replacements

I have a 12V air compressor(250PSI) for connecting to cigarette lighter and inflating tires. My problem is that it works with my 200SX but not with my 300ZX - and I've checked both ciggy lighters and they both work. Both cars are UK; anyone know why it only works on my 200SX?!

Also, I plan to take out the spare tyres to lose some weight - what do I need to replace them and where can I buy them - someone mentioned a compressor ? (like above?) and a can of rubber spray ? - does this make the tyre irreparable if used ?

Differences between a 200SX & a 300ZX:

300ZX sticks to the roads much better. Acceleration is less urgent? than in a 200SX. Headlights on 300ZX are crap unless on full beam. 300ZX is about 6 inches shorter than 200 but 300 is wider. 200 has 195's all round, 300 has 245's at back & 225's on front. Spare in a 300 is a narrow yellow jobby, in a 200SX it's the same as other wheels. More turbo lag in 200 as turbo is bigger than 300's. The alloys on a 200 are 15", 300's are 16". 200 feels a lot softer and looser. Petrol filler cap is on other side - right on 200 and left on 300 (easy to get it wrong when u own both when pulling into garage to fill up!). Fag lighter in 300 is under a lid, exposed in a 200. 300 has PROGRESSIVE power steering, 200 doesn't so steering at speed in 200 is a little fidgety. I like both cars but 300 is a much better car in terms of performance - the 200 is a nice comfortable drive with impressive acceleration when booted. The 200 feels a little too big and long in my opinion for the power it has (lots of body roll) -but it is impressivley quick - I can imagine it easy to lose control if driving it hard around bends etc. Both are superb for long cross-country drives - very unfatiguing. 200 does about 30 mpg to the 300's 20mpg. 200 has a much heavier(steel) bonnet to the 300's ally one.