I'm interested to get a set of wheel locking bolts.
On ebay, most of them are 12x1.25MM.
some are 12x1.5MM.

I have an original set of Punto GT wheels on my cabrio (4X98).
What size should I get? does anyone know the thread size?

12x1.25

Thanks, but I came accross different thread length:

28mm
26mm
25mm

some are
12mmx1.25mm 60° Tapered Lock Bolts 30.5mm 19mm Head

What means 60° Tapered?

In terms of choosing length, take a bolt out and measure the shank.

thread length depends on application... Whether you have spacers etc.

But if you are just wanting to get some locking bolts, take one of your bolts out and measure the length and then you should buy some no shorter and not more than a few mm longer.

Is the left picture is the way to mesure it? if so, then it's 28mm.
It's a flat washer from what I can see, I haven't found flat ones on ebay.
would a tapered one fit?

flat-seated ones are pretty rare really, i know some standard wheels use them but never seen an aftermarket wheel that does, nor have i ever seen a oem fiat wheel that uses them...

Is that one off your car? And if so what wheels have you got?

I had aftermarket wheels,

It's the same bolt without the ball thing:



I now have GT wheels, probably the guy who installed them to me took the metal parts off and left the bolts flat.

ah i see... they are wobble bolts - designed so you can fit wheels that have a slightly different stud pattern (within a few mm). For example fit wheels with 4x100 pcd rather than 4x98 that a fiat has..

If i were you i would replace the bolts with some tapered bolts asap. And you can order some locking ones at same time..

these will be fine
http://www.ebay.co.uk/itm/161414696521

and these
http://www.ebay.co.uk/itm/151394353897

There are of course different finishes and types of locking bolts but they will be fine

Should I replace them in term of safety? Are the tapered ones stronger?

Thanks, I will order.

you should use the right bolt for the wheel yes.. you could damage the wheels, the wheel bolts could come undone as well as the friction between the mating surface of bolt and wheel is what keeps it tight & you will only have a very small contact area between the bolt and wheel - essentially a very thin point at the edge of the bolt is touching the wheel whereas the entire taper with be in contact with the wheel on a tapered bolt.