i think its 2 1/4, i already have them, they are the same size as the stock center caps on my GP. the pontiac symbol is grooved, i want the the decal to be in the grooves. the more i think about it, it might be better to just paint the inside of the grooves.

the auction says they came from a Grand Prix, but not the year. here is the link Pontiac Grand Prix Bonneville alloy WHEEL CENTER CAPS :eBay Motors (item 120485486783 end time Nov-03-09 21:52:25 PST)