installed larger wheels and spare won't fit

You can go to any tire store (NTB, Costco, TireRack, etc) and have them order you a replacement. Either that or check on any of the online stores, such as http://www.tirerack.com.

first off you did not chainge your wheel base by puting 16s on your car . your allso not giving us enuff info to figure out what your probblem is why dosent your old spair work? isnt tall enuff? or did you use adapters to make your new rims fit and now your bolt patterns are different. if its a diff. in bolt paterns count how many studs "bolts" and then mesure between two studs center to center then go to the junk yard and find the same, allso try to get as close as you can on your spairs hight to your new tiers