For those people who are wondering what size wheels to get, I have some helpful information for you picking sizes and what to expect from those sizes. To start, when it comes to all the types of bumps on the road, springs and shocks help in large bumps like potholes, sudden drops or rises and raised objects off the ground, shocks and springs are meant to travel long distances to absorb the majority of movements you don't feel in your seat. Tires on the other hand give you a better ride over things like rocks, dirt as well as finishing the job of the shocks and springs after they do their work, giving very fine bump absorbtion that the shocks and springs dont absorb.
Getting larger wheels also reduces the amount of rubber your car will have which reduces the above absorbtion (unless you are going for a monster truck look with big wheels AND tires). So it's kind of a sacrifice between comfort and looks (what isn't when it comes to customizing?)
14": Standard on (most) Aveos, they have the most comfortable ride due to the size of the tires, in other words more rubber = more comfort. This size is among the most common wheel sizes due to their extremely wide spread use (virtually all sub compact to economy sized cars come with them standard). Coolness factor is low due to the amount of rubber you see (looks bad), however quite a few tuner teams who street race or do track racing use that size due to the very light weight racing wheels and the very little torque needed to make the wheel revolve once.
15": These wheels are pretty much the same as 14" in every way except for the extra inch, coolness factor is just as low as 14"s, I personally wouldn't reccomend getting 15"s because its not really worth paying more for the same look, and more importantly, 15" wheel and especially tire choices are quite limited since most car companies just drop the extra inch and use the generic 14"s.
16": These wheels are pretty much the half/half wheel choice since they lose just as much tire size as they gain wheel metal. Giving up just as much comfort in exchange for traction and stability. 16" wheels are for people who want a little better look to their cars without sacrificing as much comfort, although the change is not very noticable. The real problem with this choice is the extreme rarity of choices, 16" wheels were made popular in the late 80's and early 90's and quickly died off when compacts became really popular. There are very few good looking 16" wheels and even less tires.
17": The most common and accepted updgrade from 14" wheels primarily because it's the largest wheel size you can get before the circumferences become bigger. The real beauty of sizes 14"-17" is that all the wheel/tire combinations share virtually the same circumferences, which keeps you from having to adjust the spedometer from plus sizes.
18": For those who really want the show car look, 18"s are the best bet, but kiss all riding comfort goodbye, you might as well ride a bull everywhere. Combined with lowering springs and you got yourself a car that feels like a metal sled on concrete. Any size above 17" start to cause problems spedometer wise since they have a larger circumference, it takes a longer time to do one revolution which makes the car's computer believe it's going slower than it is, the bigger the wheel above 17" the more the difference noticed.
19" and up: For the true customizer, the 19" wheel is the holy grail, no other wheel gives you a better look for such a small car (the Aveo Xtreme on the top of the forum has 19"), however without body work to the wheel well as well as the side fenders, driving the car is not only hard but quite dangerous. If you have no body work done to it, you will have critically low wheel travel so run over anything bigger than a few inches and kiss your tires, wheel wells, and side fenders good bye. For the Aveo at least, anything 20" and up is just over kill. The good thing is that 19" wheels are also quite common to find.
