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the standard variation with BPWø12,5x30

I'm wondering whether this might not simply be an ageing effect, most likely shrinkage caused by loss of plasticiser. The reason for this is that 12.5 mm would correspond to 1/2" whereas 12 mm would be an odd imperial size

Idris wrote:I'm wondering whether this might not simply be an ageing effect, most likely shrinkage caused by loss of plasticiser. The reason for this is that 12.5 mm would correspond to 1/2" whereas 12 mm would be an odd imperial size

Hi Hugh

There are two types of the black wheels, please compare my photos , it is not ageing effect, there are two different shapes of the wheels.
Antonin

Diecast wrote:

Idris wrote:I'm wondering whether this might not simply be an ageing effect, most likely shrinkage caused by loss of plasticiser. The reason for this is that 12.5 mm would correspond to 1/2" whereas 12 mm would be an odd imperial size

There are two types of the black wheels, please compare my photos , it is not ageing effect, there are two different shapes of the wheels.

Are you sure?
What I see in the lower of the two photographs is that one of the wheels has been fitted the wrong way round, i.e with the extended hub facing outwards instead of inwards.

It is impossible to fit it in opposit way, they have long hub on the inner side ( by one wheel is this case, but it has no influence, I took the photo on the opposite wheel ).

I'm sure you're correct in what you write, Antonin, but I'm struggling with the details of the difference(s). Putting the question of the diameter to one side for the moment, is it something to do with length of the central boss?

The most visible difference is on the outer diameter of the wheels, "on the profile of the tyres". The first is more coarse, the second one is fine.

Diecast wrote:The most visible difference is on the outer diameter of the wheels, "on the profile of the tyres". The first is more coarse, the second one is fine.

Got you!
It also looks to me as though one wheel type has a flat running surface whilst the other is curved.

Hello Antonin and Hugh,

Thanks for posting these images Antonin. I agree that these are two different size wheels and different profiles. These were highlighted here when Nick started new forum.

viewtopic.php?f=3&t=84&p=1007&hilit=52+ ... 82d3#p1007

If the link does not work please have a look under Re: 52a Maserati - a question on wheel sizes started back on 20 September 2013.
My images are similar to yours.