Wheel PCD experts needed

[300bhp/ton]

I've seen listed:


5 x 120
5 x 120.6
5 x 120.65


My question is, do all three PCD's actually exist, or is it just a rounding/truncating issue that some places refer to the exact same PCD but under slightly different guises.


If they are different, are they different enough that you really shouldn't put a 5 x 120 on a 5 x 120.6 hub?

[stevieturbo]

The decimal points are so small as to be insignificant I'd say.

Probably just someone doing a metric-imperial conversion or something

[300bhp/ton]

Thanks. That was my hunch, but thought it was worth getting a 2nd opinion, as a set of wheels and tyres if pricey business.

Ta

[andygtt]

Is one a BMW offset and the other Jag?... I know a friend who had jag hubs and fitted BMW wheels as the offset was 0.6 mm different.

[Pumaracing]

300bhp/ton said:

I've seen listed:


5 x 120
5 x 120.6
5 x 120.65


My question is, do all three PCD's actually exist, or is it just a rounding/truncating issue that some places refer to the exact same PCD but under slightly different guises.


If they are different, are they different enough that you really shouldn't put a 5 x 120 on a 5 x 120.6 hub?

No they are actually different. 4.75" x 25.4 = 120.65 mm which is an imperial measurement from early Jags and not the same as an actual 120.0 mm PCD on some continental vehicles. However I suspect that a 0.3 mm discrepancy on radius is just about small enough to be catered for in the flexibility of the wheel studs or nuts but definitely not to be recommended. It'll create some unwanted stress in the mountings which could potentially lead to a failure although I suspect the chances are very small.

Sadly some online PCD charts compiled by idiots round 120.65 mm right down to 120 mm without even an indication that's it's actually an imperial PCD not a metric one. They do the same for many other imperial PCDs on British cars. Caveat internet surfer I suppose.

[dtmpower]

Get some wobble bolts to take up the slight offset in hole/thread. Make sure the hub / wheel seat is exact also.

[Evoluzione]

andygtt said:

offset

Have you been at the Sherry again?

[andygtt]

Evoluzione said:

andygtt said:

offset

Have you been at the Sherry again?

Guinness :-)

[PaulKemp]

Spigot diameter is also important
You can buy spigot converters if the hole in the wheel is larger than the hub spigot
0.3mm is neglable, steel tapered nuts and alloy wheels