When it matters material for wings carbon fiber would be the best. Try to find small flat or slightly bended (if you want to generate downforce) pieces of CF from a crashed motorcycle cover or from a racing car. Later you can cut it and tune up with sandpaper.
To achieve great speed wheels must weight as little as possible and most of all centered perfectly. Only way to achieve this is to use plastic wheels from some broken mechanism/toy car or make new ones on a small lathe (gunsmiths usually have them).
Perhaps you could try to find 4 carbon fiber fishing reel spools. They are perfectly manufactured, very little weight and their shape would allow you to achieve necessary width at contact point (15mm min).
Having a ball bearing on the wheel is also very important for achieving great speed. Nowadays they are made even very small. Anyway, taking wheels from a toy-car seam looks simplest to me (if allowed by reg.)
If you have enough time, best way would be to design the wheel, acquire appropriate material (round aluminum bar), find 4 small ball bearings (fishing reel repair shop) and tubes that you’d use as axles (use tubes/pipes to decrease weight, not bars).
You should make these wheels on CNC and if CNC is not required for wheels than a local gunsmith could make you wheels on a lathe with fittings for a ball bearings. Than you can polish the wheels using any household silver polisher (even a tooth paste will do).
The ball bearings must have slightly wider diameter than the fitting on wheel so when it is pushed in it stays firmly attached (PUSH BEARING IN USING PIPE WHOSE DIAMETER IS SIMMILAR TO DIAMETER OF THE OUTER RING OF THE BEARING!!! PUSH ONLY THE OUTER RING OF THE BALL BEARING!!!).
Same goes of axle. The inner diameter of ball bearing should be slightly smaller than axle diameter which is necessary to provide partial grip/fixation (must have greater resistance than the balls & rings of the bearing) of the inner ring of the ball bearing and rotation of the wheel only over the balls in the ball bearing. You can skip this using the glue but than you won't be able to remove wheel fromthe axle.
Use spring, plate and secure pin to secure wheel from moving axially.
Additional plate to secure ball bearing from detaching from the wheel can be added too (it is not shown on the drawing). This could also be done using strong glue.
Wheels should also have aerodynamic covers from both sides to improve aerodynamics.
I also made one very simple design (easy to make using CAD) of the car with all necessary elements (hope i didn't skip something from the reg.)
…it is said in reg. that there must be a flat space of certain dimensions for a number sticker.
