Big call-out for Leafless on this - he led me to this combination. And here are the wheels installed with the Blazer center caps:
With the these wheels and the 5mm spacers in front, my Dunlop Direzza DZ102 fit fine, with either 195/50 or 205/50, so I'm using my 195/50 at the back, where they lower it by 1cm vs. stock. The 205s at the front give a nice improvement in traction over even the 195s, and balance out the understeer a bit. I'll probably put 205s on the back when I need to, so I could rotate the tires fore and aft.
Since I transferred the 1000-mile tires I had on the OEM wheels, I can directly compare the wheels:
- The Rotas take a Lot of bump out of the bumps and potholes - the whole suspension feels more sophisticated, the ride is less jarring, and they are a bit quieter as well, since less shock is transmitted to the frame. In the long run, the reduction in unsprung weight and impact will also keep interior ticks and clicks noises down.
This is the biggest result of this upgrade - I've done similar wheels upgrades on several cars, and this is more of an improvement in ride comfort than a very similar wheel swap on my Mini S, perhaps because the Spark is a lighter car.
- Cornering traction on bumpy pavement is improved. It could be the 205-195 swap in combination with reduced unsprung mass (6 lbs/wheel is a lot on this car), but the car has more grip, thus less understeer when cornering, so you can put a bit more power down. It also feels like the lowered tail-end may have added benefits in cornering.
- Acceleration and braking - not so much. I'd guess the reduced rotational inertia might get you to 60mph .1/second sooner, but that's about it, based on some tests written up by Grassroots Motorsports a few years ago. The rough rule of thumb on wheel weight is that 1 lb. reduction in wheel weight is equivalent to 3-4 lbs. reduction in car weight, so the equivalent of maybe 80-90 lbs. less isn't going to make a huge difference. Reduced unsprung weight does keep the tires on the ground better, so the dreaded traction-control light does not come on as often when accelerating on imperfect pavement, and that might buy you a little more.
Worth $440 shipped? To me, it is, as it makes the car feel considerably less cheap, while improving some key aspects of ride and handling. Oh yeah, and I think the wheels sure look nice - all the car needs now is a huge wing at the back...
