You need to split your verts (uv mapper)

Try unclicking the smoothing function in your final rendering settings. 

I assume its the blooming of the wheel spokes that you don't like.  It's possible that when you imported the figure, it activated the smoothing function in your final rendering. --Jan

+1 on the smooth polygons in the render settings.  Thats what it looks like to me.  I had the same thing happen to a bow string and turning the smoothing off fixed it.  You can turn smoothing off for the entire scene or just for the parts that are giving you problems.

if you modelled the wheel , delete the ends of the cylinders that make the spokes . a cylinder without an endcap wont bulge because of smoothing. Unwelding(split vertex) will do the same thing .

Thanks, smoothing off did the job.
But a following question to Kuladen ("You can turn smoothing off for the entire scene or just for the parts that are giving you problems.") How this can be done, smoothing is just a checkbox in the render settings?

Ont he properties window for the object, you will see the parameters tab and the properties tab.  Click on the properties tab and there will be a checkbox for Smooth Polygons.  Uncheck that box and it will turn off smoothing for that object only.

Thanks.

You can also insure that a prop or figure will always be unsmoothed,
so you won't have to be surprised by the bulging cylinders each time!
Go through the PP2 or CR2 file and change each

smoothPolys 1

to

smoothPolys 0

If the file is older than Poser 6, it won't have the smoothPolys line,
but  you can still add

smoothPolys 0

to the file.  Insert it after each "customMaterial" line.

Just FYI, you can also decrease the crease angle and it has the same effect.
(The box just under smooth polygons in the properties window.)
I had a shotgun prop that bloomed like that on the barrel.  But I didn't want
to disable smoothing entirely, so just playing around I was able to get suitable
results by setting the crease angle from the default of 80 down to 5.
That way I still had some smoothing on the stock, but the barrel didn't
look weird.

Note: you need to leave Smooth polygons checked for this to work.

I've been trying to set up different smoothing groups - the way the poser manual says, in order to create creases, and darn Poser appears to be ignoring them. Arrrgh!

Is it possible to have different smoothing angles on a prop... or do i need to split the prop in several items, then parent them to one another to have different smoothing angles?