So what are the differences between having one or the other?
I know there is a lot of hype about having 18s but what is the reality?

 

The difference is about 25.4mm.

18" = harsher ride, and you have to be more careful about potholes.

 

Many auto enthusiasts like the look of bigger and bigger rims but only to a point of exageration or balance.

Some people think that the MINI being a small car looks about right with 17" wheels. 18"s are a bit big but workable and 19" fairly large. 20 to 22" extreme.

For practical purposes the larger the rim diameter the smaller the tire sidewall. Lower or smaller sidewalls are necessarily stiffer and that results in a usually harsher ride which on smoother roads is fine but on rough roads or roads with many potholes can be very unpleasant.

Risk of damage to the tire and rim or even to the suspension is higher with any tire with lower sidewalls. Lower sidewalls do help with responsiveness and handling is usually very good.

Tires with lower sidewalls can be expensive within the same tire model and selection can be limited to more performance oriented tires which tend to wear faster and give better handling.

Larger rims can weigh more on average but lighter rims are possible but cost much more. Still, even with very good rims the weight tends to be generous. Weight itself is not a big deal for normal street driving but for any kind of performance driving it's better to be lighter as it takes less energy/power to accelerate and brake. For relatively underpowered cars like a stock MC or MCS lighter wheels make more sense.

Large wheels tend to be helpful for any Big Brake kit. Many BBK require 17" or larger wheels but this can vary. Wilwood BBKs can sometimes fit smaller wheels like 16". Larger wheels do make the stock brakes look undersized and an 18" wheel with BBK looks more balanced.

If you have a showcar then 18" wheels make sense.

If you have very poor roads then 17" would be better than 18" and 16" would be even better. Use a 205/50-16 tire for general street use.

 

18s generally look better. Really depends on the wheel design as well as the amount of drop your running.

As for 18s on a show car.. 19s would be better suited for a show car...

 

One inch in diameter is the difference....17s look best!!!

 

And now for a different opinion about size...

Minihune is spot on about the pluses and minus of different sizes as far as function is concerned.

As far as looks are concerned it's all personal opinion.

When it comes to looks versus function my opinion is 16 is the best looking compromise. I have a set of 17" Web Spokes and they look great but my 16" Minilites make the car look like it has wheels rather than making the wheels look like it's wearing the car.

In this case smaller is better. Just my opinion.

Hope this helps...