Hi everyone,
In a fit of enthusiasm I bought some rims off ebay! (at the time I took a risk remembering that it was either 100 or 108 I needed and was tending towards the 108 being the correct figure - 
DOH!).
They are 4 x 108mm alloys made by Xtreme. Can someone tell me how I can discern whether they are multifit, or do I need to resell them and be more intelligent next time I purchase.
I suspect there is soon to be a set of rims being put in the for sale section.
Multifit rims have lots of stud / bolt holes so they can fit different PCDs.
If yours only have 4 or 5 (if a newer car) holes and they are 108 PCD you won’t be able to use them on your car - period.
Multifit alloys would have eight bolt holes around the centre of the wheel, four of which would have a diameter of 108 and four of which would have a diameter of 100.
If you’ve just got four holes, and they’re 108mm apart you have three options:
Sell the wheels on ebay and buy a set that fit. I wouldn’t advertise them in the for sale section here as they won’t fit many cars on an MX5 forum!
Buy adaptors. This is expensive (possibly more than you paid for the wheels) and some say less safe. You’d have to really like the wheels.
Buy a different car. Sell your Mazda and choose from a wide range of Fords, Citroens and Peugeots; they’ll probably go straight on. You’d have to really like the wheels. 
Thanks for the advice, much appreciated.
in regard to 3), I seem to remember a retort about dead bodies (my, over etc), unless of course someone loved my rims so much they were willing to give me a formula 1 car in exchange for them - and they are highly desirable (lol)!
Would the seller not be prepared to swap the wheels for a correct 100 PCD? ( I am assuming you bought the wheels from a company rather than an individual)
Not been on for a while, varous things going on. I suddenly remembered theres a scrappy 3 miles away and took to diligently visiting every few days until a suitable set came in. So have some fox racing rims now with brand new T1rs on (as completelt mismatched tyre were on them, mosty in !"£$ condition). 2 weeks ago had to get a fifth T1r as a stray (from the gutter) drill bit did what it was designed to do and went straight through the tyre, luckily at a slow speed, and close to the tyre fitters at that!
Still have the origonal 14" and am trying to sell the misbought 15" on preloved.