Tyre / Rubber
You've found your perfect rim, but you wouldn't want it to be the first thing to kiss the road, so you need some rubber.
There is a time when wheels are made out from wood/metal and rubber isn't even gaining popularity with condom industry yet.
Anyway, if you have a car you will notice the tires and wheels are ROUND. When your car is moving, the tire doesn't changes shape in to SQUARE, which means theres only a small part of the tire is in contact with the road AT ALL TIME.
And it is that small stripe of rubber thats going to determine whether you can brake, or you'll go through the Pearly Gates with bits of car stuck in you. Like:
Don't really fancy ending up this way, thank you
That is why you don't drive fast in rain, or when your car have poor grip on road. This is also a phenomenon known as Aquaplanning, google it to find out more.
The only reason you can cruise smoothly at 150KMph and still able to steer the vehicle is because of grip. If you can't steer the car, or you feel the car is wobbly, step on brake slowly. You certainly don't want to upset the balance(which its suffering to gain) and sent everyone spiraling to Heaven/Hell/ Automotive gaveyard.
Because I'm a little lazy, I'll recommend you take a read at Christopher J Longhurst's CarBible on Wheels and Tyres.
I hope you have a good read. Till then.
