hub rings

i really like the simple sturdy style of the American Racing Ansen Off road wheels....so i paired them with some cooper stt pro tires. the wheels are 18x9 with a center bore of 108 mm. Got a hub ring in order to center the wheel on the stock 77.8mm hub. Only one problem....This american racing wheel has a push thru center cap so i can't put the center cap on the wheel with the hub ring in place. the next smaller size hub ring is 106 mm so that wont work. any ideas on getting a push on center cap for 108 mm wheel center bore? or how to get a 77.8 mm (even chevy size 78 mm) to 107 mm hub ring? i figure the 107 will probably give me enough room to push the center cap through the wheel and still mount the wheel over the hub ring.

you can look at my pics and zoom in....you'll see the awesome wheels and cooper stt pro tires with the exposed center hub and yep, axle nuts....ok for now but don't want to leave em like that.

thanks for any ideas / help.

12 titan - over