Can Koni FSD shocks be use with 18" wheels? If not, what size of wheel are optimal? And how hard are these to install? If rather not have to pay for a mechanic, but will if needed. Thanks for your time!

 

A larger wheel will increase the unsprung weight and require a heavier duty strut. The FSD is designed to adjust to road condition and provide as consistent a ride as possible. They should do just fine for you. To install, you need the whole car off the ground, appropriate wrenches, spring compressor, torque wrench and proper torque information for reassembly. While you have the rear end broken down one of the best mods for the money is a heavier rear sway bar. Check some of the vendors listed in the Directory. Most guys install either a 19 or 22 MM RSB.
I've had FSD's for a couple years and love them.

 

You can use FSD's for sure.

Here is a how to with pics, Pelican parts has an article as well, you'll save yourself a few hundred bucks, +1 on the rear sway bar. Do it at the same time

http://www.minicooperspeed.com/mini-...-installation/

 

Let's be really clear.

If you use 18" wheels that are near factory option size, and tires about the same section width, then yes, you shouldn't have any problem. You aren't going to be able to use 18x9 et 50 wheels, or 275 width tires.... Fitment becomes a bigger issue the more you lower the car.

As for wheel weights, again that depends. some 18" wheels are lighter than the factory 16" wheels.

You have to remember that there are three properties that are important when looking at wheels. Strength, weight and cost.

Light and cheap won't be strong
Cheap and strong won't be light,
And lastly, light and strong really won't be cheap. (BBS, Fikse, HRE, almost anything that's actually forged)

So, of the three properties, you usually only get to chose two