factory:
E60-15s front (225/60/15)
G60-15s rear (245/60/15)

but, if you are not going with reproduction Polyglas GTs:
235/60/15s front (F60-15)
255/60/15s rear (H60-15)
look better

Do you have 15x7" rallye wheels, "450" $$ wheels, or other?