Thanks for your response & please correct me if I am wrong.
Alloys at 15'x8'= 381mm x 203.2mm however alloys are measures from the inside face of outer rim of alloy.
on the otherside
225 x 55 r15 the 55 is 55%of the width at 225mm and the 225mm is measured to the outer face of tyre (the overall) not the inside face of inner rim of alloy. The rim is approx 5mm + perhaps 5mm tyre overhang both sides so, 203.2,mm + 2x5 + 2x5 = 223.2mm ish i.e. 225mm
Overall diameter match to original, thanks to Toopy
195x70x14 = 355.6 + 136.5 + 136.5 = 628.6mm
225 x 55 r15 = 381 + 123.7 + 123.7 = 628.4mm (this may hit arches)
for a summary you need a 9" tyre for an 8" alloy.
http://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator
Should i use 205x55x15 to the front and 225x50x15 to the rear? Car is 260z 2+2 and is lowered.
15' = 381+112.7+112.7 = 606.5 fronts 205x55x15
15' = 381+112.5+112.5 = 606 rear 225x50x15
or
15' = 381+102.5+102.5 = 586 fronts 205x50x15
15' = 381+101.2+101.2 = 583.5 rear 225x45x15
Obviously this will have an implication on gearing and speedo.