i mounted 205/50r16 on the rear of my S today JUST to test if it would accelerated faster. it seemed the same for acceleration, the only thing i noticed is the car seemed to need more gas at cruizing speed like 40-60ish to keep it going, I suppose theres less inertia in smaller tires. I've seen a couple posts about getting lighter wheels/tires setup's. I can now say on a S you will not feel that difference. I remember putting smaller tires on my gti and definetly noticing a difference. My guess is the power has to go through the whole driveshaft the diff and axle's so taking off a few pound's off the tires isnt going to be much compare to the whole driveline... thought's questions flames im open..

 

Moved to Wheels and Tires

 

Its always a benefit to shave weight off of a rotating mass especially wheels/tires. The S2000 cant change physics... I noticed the benefit of better acceleration when I had a '92 miata and installed lighter weight tires/wheels on it.

 

Butt dynos and accelerometers are notoriously inaccurate, so I wouldn' t put much stock in any of this. Regardless, putting small tires on this car is at terrible way to improve performance. If you want a shorter final drive, it's far better to swap the differential gears out.

 

true it was just a test, I thought it would be noticable is all

 

what size tire were you comparing from? A bigger tire would require less throttle input to maintain same cruising speed

 

Actually, smaller tires can be a good way to improve performance if you could get them as wide as taller tires. Less unsprung and rotational mass, better overall gearing, better braking resposiveness (more braking g's per pedal effort), and lower c.g. without compromising suspension geometry. My Z is faster on 225/50-14s than on 225/50-15s. But my money would be on 225/50-16s giving better overall performance than 205/50-16s of same model tire.

 

Actually,the taller tire should require slightly greater throttle input, but should give slightly better fuel economy.
Consider that at a given speed, the same amount of power is required to propel the car (assuming for the moment that aero drag is the same with the taller or shorter tires). With shorter tires, engine rpm will be higher and engine torque required to maintain the same road speed will be lower at the same power output. Less torque required will generally mean less throttle in the same gear. But greater rpm => greater engine frictional and pumping losses, hence worse mpg. Slightly wider throttle opening at lower engine rpm will be more efficient.

 

225/45 16 is a size