will putting very large wheels on a car have any negetive effect. i know that the wider the wheel the beter but will a 16 inch wheel perform beter that a 21 inch wheel. or is there no difference
The added unsprung weight and inertia of the larger wheels can have
negative effects on handling, braking, and acceleration. Acceleration will
not be as good as with the 16's due to the extra weight and intertia of the
larger wheels....dyno tests have shown actual horsepower losses when
changing to larger wheels. Handling will also be effected slightly because
of the added unsprung weight and the fact that you'll have to run such a
low-profile tire on that size rim will make the ride a little more harsh.
You'll also have to watch for curbs and pot-holes with big rims like that.
On the other hand, just bumping up one size, to say 17's, shouldn't effect things nearly as much...especially if they're light-weight rims. I switched from factory 14" steel rims to 15" aluminum rims and I was able to reduce understeer noticeably (due to the stiffer side-wall), but there is a little more road feel transmitted through the steering wheel...and not exactly in a good way.
Running a rim of 21" on a vehicle that originally came with 16" rims, can also cause premature ball-joint, tie rod, and strut/strut mount wear and/or damage.