Ultima Sports, spider owners

[highflyer]

Hi Sports Spyder owners I have a set of 17" rears and 16" front Image Ultima wheels but struggling with replacement tyres, at the moment they have Hooster slicks P315 / 35 ZR 17 rears and 210 / 610 R 16 fronts I'm looking for road tyres but can't seem to be able to get the rears can anybody help with replacements please
Regards Russ

[highflyer]

Hi Dom the rears appear to be 12" 1/2" wide and across the face of the wheel 18" 1/2"
Fronts 9" x17" that is across the front of the wheel bead to bead as you can tell I'm not very good with wheels n tyres