best size , offset for 15inc, lowered 60mil?

[TUBZGSXR]

i need sum knew front tyres as my trackin was totally out an there worn to feck on the inside, goin to get the trackin an new tryes sorted 2mora, im just wonderin wot the best size is? i had 195 50R 15, an still have these on the back, but wot is the best size realy?
thanx

[Philsutton]

i used to have 195/45/15 on my 15s but i think 195/50/15 are cheaper. might be wrong though.

[Aragorn]

195/45r15 are the best size as its closest to the original circumference and the smaller side walls will give less flex