Cocktail shakers need to exist for sure. But-might sound odd, but make sure there's no "natural goodies" involving your wheels: water in a tire, mud daubers makinging big tubes on the inside of a wheel, flat spots from sitting... I pulled a flat tire off my dads F150 that was sitting in the barn for a few years and it had all sorts of bug junk stuck to the inside of the fronts.
'68 400HO Coupe, 4 spd, 259 interior, Windward Blue. My other car's a Johnson 15 outboard on a '61 Starcraft rowboat... Just sayin'.
