1. step:
ok, here a small tutorial how to make a small fly wheel toy or similar things.

we will start with the wheel. the very first step is a disc. since we want to create a wheel with 5 spokes we need a disc with 20 sides
i think it's better to use rims with 3 or 5 spokes (or similar things) because people are thinking that symmetrical or mirrored objects are unnatural (ok, that rim is both but you got the point). for our car, the original object is also armed with 5 spoke rims. the next step is bevel, we bevel both sides of the disc, one step for the border of the rim, 2 steps for the definition of the inner rim and the last 2 steps for the hub
we're kicking the both polygons from the middle and welding the points with average weld
next step is to select the border on both sides and the 5 spokes (the forthcoming spokes) and to smooth shift those polygons 3 times
following that step we deselect the hub and the spokes and smooth shift the border 2 times more
after deselecting everything press tab to switch to subpatch mode. if everything is done like we want it we oughta get an object like shown in pic
some additional smooth shifting and we have the lower part where the tire snaps in and with some rotating of some points between the spokes we will get sharper corners
with some additional steps we can change the hub to a more technical shape. i've added some nuts (not the ones from the trees) like shown in pic 8 if you want to spend some more time you can remove some polygons from the border of the rim.

so, the next step is the tire. if you think the rim is heavy on polycount stop reading now ;-)

because we want to create some impressive profile for the tire. the primitive is, as usual, a disc. depending on the amount of profile we need a disc with 80 or more sides. we use bevel to create the base shape of the tire. create smaller disc with that tool with a kind of slope to make the tire look round on the border. the last bevel of the both discs should make them touch together. delete them and set the points to the same value and merge them. if my explanation isn't that bad you should get a result similar to picture 9
now we have two possibilities to create the profile. first one - select all the polies we need for the creation of the profile and smooth shift those polies to the shape we want.
second one - work on a segment of the tire, smooth shift only one part of the profile, kill the other part of the tire and clone the segment with the profile. the result should look like pic 11
now press tab and you have an object like shown in pic 12
use the knife tool to get some sharper stops of the profile and rotate the inner points of the tire to get the v shape

that's all for modeler so far. switch to layout, add some bumpmap for scratches and broken parts and some dirty maps for a more natural look of the tire. depending on your subpatch level you can make nice close ups of the tire without that ugly polygon style.