i think 18's are way too big for this car im sure you'll come across issues with the wheels rubbing especially when turning. seen a spark in person at the auto show and it's wheel wells don't look like they can take a wheel that big.
Larger wheels usually mean lower profile tires such that rolling diameter is close to stock and no correction is necessary.I don't think 18's will work, but I may be wrong. Wouldn't the speedometer and shift points (if auto trans) be incorrect when running such large wheels? Or can the Spark's computer be calibrated by the dealer to account for different wheel/tire sizes?
17s will be the biggest you can go for the front...
if i eyeball it its possible to get 18s in the back but then you run into balance issues...
tire size will be 205/45/17
anything bigger will hit a plate in the front ...
if you check your cars front tires you can see the plate im taking about ....
How big of a wheel have you been able to put on or seen on a Spark?
Chevy Spark's come with 15 inch wheels from the factory without anything bigger as an option.
17's seem to be a size that will work well, but what about 18's?