I have 2 Pantera's that I have put Avon street tires on that are as close to the original Arriva dimensions that you will find.
They are Avon
275/55/R15 REAR
215/60/R15 FRONT
came from http://www.rogerkrausracing.com/
I spent a lot of time comparing actual dimensions of width, sidewall height, section width, all of which are on RogerKrause website.
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