I don't have much knowledge about wheels and tyres. A friend has a set of Abarth 123 wheels and tyres for me. But my 1.2 pop only has a set of steel wheels 175/65R14 5.5jx14. But I can see that it can be fitted with a 195/45R16 wheels too.

The spec given for the new set of wheel is 4x100, 17x7,45 offset (Abarth 124 spider wheels). It is certain that it will fit Mazda MX5 without any alteration.

Can someone explain what these numbers are about and whether it will fit a 2013 500 1.2 pop.

While they can be made to fit, they won't just bolt on and will require special bolts and possibly spacers. You'd be better off finding some Abarth 500 wheels.

A quick and dirty guide to wheels and tyres

Diameter and Width
When looking at wheels this is usually expressed like 14 x 6J
This means a 14" diameter and a 6" width
When looking for tyres to fit, you want something which will fit the width of the wheel, but with tyres the width is expressed in mm ie. 195/45r14
This means a 195mm wide tyre, with a 45% sidewall (45% of 195mm = 87.75) for a 14" rim.

Rolling Radius
When considering wheel and tyre combinations, you need to keep the rolling radius within a few % of the OE spec or you'll throw the speedometer out.
There are sites you can use to calculate this - just search for rolling radius calculator.

Pitch Circle Diameter
How many bolts, and on what size circle?
FIAT (generally) use 4x98 which is 4 holes on a 98mm circle. The 124 and Grande Punto use 4x100, which can be corrected with wobbly bolts but wait - there are other things to take into account!

Offset
How far from the center of the wheel the 'mating face' (the bit that bolts to the car hub) is, and in which direction - positive offset (eg ET45) is further in towards the car (and can be corrected with spacers), negative offset (eg ET-45) can't.

Centre bore
This is how big the hole is in the centre of the wheel. It needs to be tight to the hub to stop the wheel moving around. For a 500 it's 58.1mm, for a Grande Punto it's 57.6mm. Because of this, despite being able to correct PCD with wobbly bolts, the Punto wheels cannot be fitted to the 500 without having the centre bore machined out.

I'm sure I've missed something, I'm just about to leave work

The abarth spider wheel centre bore is 54.1mm and 1.2 pop is 58.1mm. It follows that it will not fit on a 1.2 pop.

Can it be saved by during spacer? Some says that the wheel can be held by the bolts perfect fine.

I am planning to use wobble bolts to allow 4x100 to 4x98 difference.

If the wheel centre bore is 54.1mm and the 1.2 pop hub has a 58.1mm diameter stub, then the wheel won't fit over it.

You need to get the wheel bore machined out to 58.1 mm.

The only workaround is if you use a hub spacer with a 58.1mm notch on the back and a 54.1mm stub on the front... but these will be quite impossible to find (i.e. they're a custom made job.. ) so it's cheaper/easier to just bore out the 124 wheels.

In any case, if you consider the offset of each wheel, you won't need spacers.

The 124 wheels are 45mm offset. Your 500 is almsot 99% going to have an offset of 35mm (but check what's on the rim, after the "ET" stamp.. that's the offset).

That means the centre line of the 124 wheels will be 10mm further inside the wheel arch.. but since the wheels are 1.5" (38mm) wider, then each rim will be 19mm further away from the centre line of the wheel.

So (compared to the 5.5" steel rim) the outer rim will be 9mm further out than the rim of the steel wheel (10mm further "in" because of the offset but 19mm further out because of its extra width), if that makes sense. You don't need spacers.



Ralf S.

I report on what has happened since my first post.

I went ahead and had spacers/adapters made. The thickness of the spacers/adapters is 20mm with the objective to have the wheels flush with the fenders. It works pretty well after they were made and installed. Since the wheels are 205x45 17. The ride quality is more stiff and bumpy, so probably not suitable for someone who is asking for a gentle/comfortable ride. However, the look is really good with bigger and sporty wheels compared to stock steel wheels with covers.

The story however does not end there. One week after the wheels were installed, I took the wheels out and was thinking to re-tighten the nuts again to spec. On a front wheel, one nut was stuck with the stud when it was removed with hand wrench. I changed the direction to tighten nut to see if I could get out of the situation. It did not work so I kept going to unscrew the nut anti clockwise, Finally the stud snapped only by using hand tool. I also found that another nut that I managed to unscrew, the tip of stud was also broken off.


My worry is that the studs on the wheel are not up to standard. I don't know what standards should it be though. It is common sense that the stud should not be broken off just by hand tool. Further research shows that the stud should probably be using 8.8 grade carbon steel or 8740 chrome moly alloy.


Would anyone has any suggestion or experience on this topic? What should I look for when ordering the stud for the spacers.

Normally, Fiat has bolts for the wheels, not studs with nuts.
So are those spacers the kind that has 5 holes and just need longer bolts or are they fastened to the car seoerately and have inbuilt studs that then use nuts to fasten? In the latter case, I would expext the studs to be 12.9 strength.

Nut stuck on the stud may have been fastened wrongly, corrupting the threads. Happens sometimes when nuts are not placed correctly and the impact wrench used improperly.

In any case they should not be breakable with a hand tool of 1ft leverage unless you are a 300 pound gorilla.

Yes.. the studs sound like they're too soft. I'd go for 12.9 like Gina says.

Meanwhile, post some pictures of the spacers on the hub, so we can see what you're doing.


Ralf S.

On the photo, you can see one of the stud is shorter after broken off. The manufacturer cannot tell me what is the spec for the stud. The spacer is bolt onto the original wheel hub by using original bolts. It works well but the quality is suspicious. I know that the alloy spacers and studs are coming from China. The spacers are milled on location.

I am now looking at Eibach and they have much better quality assurance. The spacers are TUV certified. The spec given by Eibach for bolt used is 30MnB3 and spacer is made of AlCu4PbMgMn, google search tells me an equivalent to 10.9 grade steel for bolt. They have certificate testing on Fiat 500. It is apparent that Eibach is quality product. Price wise is 25% more though. 4 spacers made is more than what I paid for 4x Abarth wheels with 205x45xR17 tyres.

The attached photo shows the wheels fitted before the studs were broken off.

here is the full view of the car

Easiest and cheapest would be to press out the studs (might work on a vice, if not, hydraulic press) and use 20mm longer (good quality!) wheel bolts. The aluminium disc itself does not have to hold much then, so that should work fine.
Alternatively replace studs by good quality ones if they fit the existing hole in the spacer.

Could you not replace the existing original studs with longer ones?

Now that I've had my breakfast (Cornflakes and a jam donut) my brains are working better and I have a different suggestion. In no particular order;

1) I told you that spacers would cost more than the wheels. Did you listen...?

2) The stud should not shear, bend, distort or snap under normal use. What is the diameter of the spacer wheel stub, in the centre of the spacer? If your wheels are 124 wheels (unmodified) then they have a bore of 54.1mm. The stub should therefore be 54mm so that the wheel fits on it and *the stub*, rather than the plasticine studs, supports the weight of the car. If your stub is too small so that it's a loose fit inside the wheel bore, it could be that the weight was resting on one of the studs.

3) I presume the studs are spaced at 100mm PCD to match the wheels, so you don't have anything odd going on with the angle the studs project from the spacer? They should all be hosizintal (could be an optical illusion of the photo, but in the photo they seem to be sticking out at an angle).

4) You don't necessarily need Eibach spacers or too much further expense but when I'm in bed at night worrying, I'd wonder whether the spacer is also made of plasticine, like the bolts. The spacer will certainly not get as much torsion on it as the bolts, since it's bolted to a flat face (the axle hub) and can't bend so to make it fracture.

If you just replace the studs for now, I would still remove the spacers from the car's bearing hub every so often (every couple of months.. or until you worked out that there's not going to be a problem) to check for cracks or fractures around the stud holes and around the wheel bolt holes (that hold the spacer to the hub). Any of those come apart and you'll be on three wheels.

5) Are the wheel (i.e. stud) nuts cap nuts, or plastic covers? If they're cap nuts then you don't need *longer* studs, otherwise your nuts will not tighten the wheel properly - they'll just wind onto the end of the stud before the wheel is tight. You need better quality studs.. in 12.9 grade.

If you have a collar type stud extractor that grips the shaft of a stud, use that to remove the studs. They could be pure studs, that are screwed into the spacer clockwise from the front... but they look like they could also be bolts... screwed *through* the spacer. If you remove the spacer you'll be able to see which it is. Ahhhh

I'll be amused (not in a good way) if they are regular hex-head or allen-headed bolts screwed in from the other side of the spacer... but anyway, once you have the bolt or stud out, whichever it is.. you'll know what/made of proper metal you need to track down to replace them with.


Ralf S.

Just got a reply from Eibach, they do make hub centric spacer for Fiat 500 and it is TUV certified. However, they will not entertain an adaptor type ie custom to fit an Spider Abarth wheel to Fiat 500 pop.

The only solution now is probably to get a better quality stud, 10.9 or 12.9 grade. The studs are pressed into the spacers. However, it is good question whether the studs were pressed vertically into the spacers. I have not had a chance to study that. At the beginning, I was trusting the professional to do professional job. I agree that the spacer itself will not have a lot of force as it is flat and sits on the lid of the wheel hub. That is the whole idea of having a hub centric spacer. I agree all the precaution and continuous monitoring.

At this point I'd have given up, punted them on ebay and bought some Abarth 500 wheels

Press out or cut off the studs, get M12 x1.25 x 45mm wheel bolts (original bolt lenght is 24mm) with wobbly cones and fix the wheels directly through the remaining 4 holes in the spacers...

That ^ would work too... although the spacer would come off every time the wheel was removed, which might get on your tits when trying to get the wheel, spacer and hub holes all lined up to refit the wheel. But it sounds like the best idea so far (I was waiting to see who would think of it first).

You can get bolts of the correct length you need.. but check the length. Stick one of your existing bolts through the wheel, then hook the spacer onto it and measure the length of the bolt thread still protruding out of the other side.

You need at least 18mm (rule of thumb is 1.5 x the bolt diameter) but go for a length that just about starts to protrude out of the back of the hub. Don't go too long otherwise the bolts will pass through the hub and foul on the brake caliper/carrier as the wheel turns.

As a caution, don't just add 20mm (the width of the spacer) to the existing bolt length, since different wheels have different offsets for the bolt seats. The Spider ("Mazda") wheels might have a bolt seat that sits further in or out compared to the 500's (Speedline?) wheels... so measure the length of bolt you need, rather than just assume you can just add the extra 20mm.


Ralf S.

Great advice. I have learnt so much about wheels now. It all worths it.