I have a set of 20x8’s that came off a C2 and they are running 235/35R20s. I’m fairly sure Vaughan’s C2 has the exact same tyres and size from North Hants but I’m not sure about his C3. The 235/35R20 is a slightly smaller diameter than the stock 225/70R15s on a C3, so you could go for 225/40R20s but these seem to be quite a bit more expensive than the lower profile 35’s. Depending on the year of your C3 if you go too much wider then you might have issues on steering lock and/or interference with the parking brake cable bracket on the rear swing arms.
Rim wise, mine are American Racing Torq Thrust 2, 5x120.65 stud fitment, 8 inch wide, ET0 offset (4.5 inch backspace).
I haven’t got around to fitting them to my C3 yet so unfortunately I don’t have any fitment pics.
Pic of them on the C2:
Thanks, yes I'm looking at those or the 338s that come with grey centres and a bit different dish, also the 245/35ZR20 with are virtually the same and extremely reasonable in price, mines an 81 and someone on another message board recently advised me that his were fine with this set up and you've pretty much confirmed that, so here's hoping, will look forward to seeing how yours looks when they're on
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