Bought some 18" rims and have a question

[iceberg]

Nice car CK! I bought the same 18 inch Sport Ed 4 set from Tire Rack last summer. I don't have the money for Michelin and went for Sumitomo. Tire Rack also balanced the set but I was getting vibrations at 70 to 80. The car runs great when I had my 17's with complete suspension upgrades. Turned out, the original Porsche metal tire valve caps that I took from the old set and put in the new ones. They screwed the weights. I had all 4 wheels forced balanced at a local Firestone shop with the metal caps. Runs perfect now.