Hello all, I recently bought some replacement rims with winter tyres for my recently bought 2nd hand 500C.

Problem is, despite being the right spec according to Tyres Online, they don't fit. On closer inspection, the OEM wheels have 8 holes in them, 4 for the wheel bolts and extra ones in between to fit the "lugs" that protrude from the "plate" that you bolt the rims to.

What are these lugs? I've never seen them before. I thought they could be tyre pressure contacts, but to my knowledge the car doesn't have a tyre pressure monitoring system.

Thanks in advance for any advice.

snoozeboy said:

Hello all, I recently bought some replacement rims with winter tyres for my recently bought 2nd hand 500C.

Problem is, despite being the right spec according to Tyres Online, they don't fit. On closer inspection, the OEM wheels have 8 holes in them, 4 for the wheel bolts and extra ones in between to fit the "lugs" that protrude from the "plate" that you bolt the rims to.

What are these lugs? I've never seen them before. I thought they could be tyre pressure contacts, but to my knowledge the car doesn't have a tyre pressure monitoring system.

Thanks in advance for any advice.

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Hello and welcome.

The lugs are there to aid in initially positioning the wheel when fitting it; they also help to initially locate the front discs.

You could remove the lugs to fit your wheels (they just unscrew), but the wheels could also be wrong in other ways. The 500 uses a 98mm pitch circle for the 4 main securing holes, unlike the 100mm pitch found on most other cars. If the wheels you have bought are 100PCD, then bolting it on with standard wheel bolts won't work and will be unsafe. You could fit wobbly bolts to take up the difference, but it's a bodge. If the centre hole is the incorrect size, you'll struggle to get it properly centered.

Personally I'd just return the rims & tyres, as they clearly don't fit a 500.

Hello, thanks for your reply and welcome. The wheels are 4x98, with the full description as follows:

INTER ACTION Black Ice 5.5x14 4x98 ET35 58.1, NOIR MAT

So, you're saying that they don't do anything, other than just make the OEM wheel easier to mount and, assuming I can mount the new wheels properly, I can just unscrew them?

snoozeboy said:

So, you're saying that they don't do anything, other than just make the OEM wheel easier to mount and, assuming I can mount the new wheels properly, I can just unscrew them?

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Basically yes, providing the PCD & centre hole sizes are correct for the car. All the required clamping force is provided by the wheel bolts.

Lots of other marques don't have these lugs; having them on most Fiats is a nice touch which makes wheel changing (and brake disc replacement) a bit easier, particularly if you have to do it on a dark stormy night at the side of the road. But they're not essential and can be left off. Just unscrew them with a suitably sized ring spanner. Keep them for when you refit the summer wheels, and don't overtighten them when refitting. I'd suggest keeping them in a bag tied to one of the wheels through a bolt hole, that way, they won't get lost or separated from the wheels and you'll be able to find them when they're next needed.

Note if your car has drums on the rear removing the small pins may allow the drum to rotate on the shaft (if you turn the wheel when offering up) this would then prevent the bolts going in, so they do serve a purpose, though as long as you have the hand brake on the problem should be lessened.

John202020 said:

Note if your car has drums on the rear removing the small pins may allow the drum to rotate on the shaft (if you turn the wheel when offering up) this would then prevent the bolts going in, so they do serve a purpose, though as long as you have the hand brake on the problem should be lessened.

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It's certainly possible, but in practice not likely; corrosion usually binds the drums to the hub, usually the problem is breaking the bond to get the drum off. This obviously can happen on any car without locating lugs and with wheel bolts instead of studs, needing about four hands to line everything up; one reason I like Fiat's design.

Hint: the holes in OEM drums which the locating pegs pass through are also be tapped (not all aftermarket ones may be); you can insert a couple of suitably-sized bolts (one size larger than the locating pegs) to extract a sticking hub.

ok, all done, new rims on and everything seems fine.

Thanks a lot to both of you for your help.

SB

jrkitching said:

It's certainly possible, but in practice not likely; corrosion usually binds the drums to the hub, usually the problem is breaking the bond to get the drum off. This obviously can happen on any car without locating lugs and with wheel bolts instead of studs, needing about four hands to line everything up; one reason I like Fiat's design.

Hint: the holes in OEM drums which the locating pegs pass through are also be tapped (not all aftermarket ones may be); you can insert a couple of suitably-sized bolts (one size larger than the locating pegs) to extract a sticking hub.

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Thanks JR I only said as when I replaced my hubs they then spun round easily(new), but the extraction bolts have the side effect of destroying the shoe retaining pins which are still stuck on the hub lip being a total pain to remove, and in the process can pull out the wheel cylinder pistons, then you've got the totally seized/then snapped off bleed valves,,,,,,,, don't you love the 500?

John202020 said:

don't you love the 500?

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The best way to deal with this is to remove the drums as soon as you take delivery of the car when new, derust, paint, and replace with antiseize grease on the mating surface with the hub.

Hardly what you want to be doing when you've just spent new car money.

Here's a quote from this old thread way back when I first got my own 500.

jrkitching said:

...but it would seem it's going to need a lot of pampering if it's to keep its good looks.

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Prophetic words?

and since we're drifting off topic already, here's another quote one from back in the day.

jrkitching said:

I'd suggest keeping them in a bag tied to one of the wheels through a bolt hole, that way, they won't get lost or separated from the wheels and you'll be able to find them when they're next needed.

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I'm sure you mean attached to the wheels not in use, ready for when these are replaced in the summer. Took me a moment to realise this. First thought was seeing them rotating at wheel speed, wondering how long before they let go.

My classic Pandas only had one stud per wheel, as did the Uno I think. The second hole was filled with a bolt with a very thin head. A set of these, 8x, would fix the issue, unless the wheels are tight against the hub at this point. Item 4 in the pic.

Ideally needs someone with a classic Panda to confirm the thread size and length to be sure of a fit.

portland_bill said:

I'm sure you mean attached to the wheels not in use, ready for when these are replaced in the summer. Took me a moment to realise this. First thought was seeing them rotating at wheel speed, wondering how long before they let go.

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Now that really made me smile. Certainly not an interpretation I'd even thought of!

(obviously I meant attached to the wheels not in use, just in case some eejit tries the alternative interpretation & then blames me :bang

jrkitching said:

You could remove the lugs to fit your wheels (they just unscrew)

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Thus saving ~100g of rotational/ unsprung mass

UFI said:

Thus saving ~100g of rotational/ unsprung mass

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Colin Chapman would have loved it. One of the most inspirational automotive engineers to have lived.

UFI said:

Thus saving ~100g of rotational/ unsprung mass

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Possibly a bit over zealous to think 8 little bolts weigh 100g

AndyRKett said:

Possibly a bit over zealous to think 8 little bolts weigh 100g

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Knowing UFI he probably weighed one (it's good practice to weigh things before posting ).

But whatever the weight, it's weight that's close to the axis of rotation so it won't make much difference to the rolling inertia, which is more important than just the mass of the wheel & tyre assembly.

OTOH, fitting wider rims & tyres, where the larger part of the weight is much further from the centre of rotation, will have a significantly greater effect.

I think he might have weighed them, as I just did.

8 of them weigh 115g in total.