Warpage
not to highjack, but what do you put on them to make them stay that way?
For the old school look on the slotted polished aluminum wheels I use WD-40 and fine steel wool to clean and shine them and protect them.
Easy to go over them again after a year if you want to freshen them up again this way. Final wipe down and polish with an old clean T Shift, soft cotton cloth. The WD-40 protects them from the elements too.
People use the Mother's Aluminum Polish too, but this gives more of a chrome look to the wheels and takes an aweful lot of work to get them there and keep them looking that way.
I don't care for the chrome look finish on the Aluminums, more of a brushed look or a lightly polished look is what I feel is correct for the period they were popular, and are still popular today.
Just like the Aluminum Wheels on my Truck, more of a brushed look and very easy to maintain.
Even WD-40 and a a scotch brite pad and wipe down polish with a soft cotton cloth gives a nice slightly polished brushed look.
Going with the so called grain of the wheel to create a nice uniform brushed pattern and not a bunch of cross hatching like inside a cylinder wall.
That's why I like the Aluminum wheels, you can always bring them back to shine, unlike a chipped rusted chrome rim that pretty mush makes those junk when they reach that point.