Mr

[Chandler4821]

How can I make 4x100 alloys fit my fiesta with 4x108? 

[robbyvrs]

new hubs

[ThaiFiesta]

Hub adaptor spacers

[DG97]

As above, hub changes or adaptors or are the two choices, either that or a set of alloys that will fit 

[robbyvrs]

You can buy wobble bolts as some people use them on VWs, etc to make 5x112 fit 5x100 - not very safe though

[isetta]

I am not sure of this.

Mazda 2 of the same era as the Fiesta is the same car underneath I think. I believe Mazda and Ford designed the car together. 

I believe Mazda2 uses 4 x 100 wheels (don't confuse with earlier Mazda2 which used 4x108 wheels).

It might be the case that you can swap the hubs (and discs/drums) from same era Mazda2 with the Fiesta.

Don't take my word for it but it might be worth looking into further.

Of course getting some 4x108 wheels would be easier.

You would also need to check size of hole in centre of wheel and the offset.

(My wife's 2010 Mazda2 has FoMoCo (ford) on the front calipers and the pads look to be the same as my 2015 fiesta)