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"Thems the brakes," Part 6 Torque, Traction, Tires and Brakes, Oh my!

951 Views 5 Replies 4 Participants Last post by  marichardson
For Bill: Be careful what you ask for, you just might get it!
First: A quick Physics lesson. Torque is a twisting force that tends to cause rotation, or in the case of brakes resist rotation. In the US torque is measured in Foot pounds. Think of a one foot wrench handle with one pound on the end. (one foot pound) Horsepower is the ability to produce torque in a set amount of time. 1 Horsepower=550ftlbs per sec.
In a car engine in order to produce more horsepower you need more torque or higher rpm or both.
Brakes are only as effective as the tires and wheels and vice versa.
When you buy a tire you see numbers on the sidewall like P235/50/18 H. Passenger tire, 235 mm tread width, 50% sidewall to tread aspect ratio, and H speed rating. But there's more: On the bead of the is a serial number, and build date like 4016, which means 40th week 2016. (By the way fresher tires are better) But wait there's more: you'll also see; Tread wear 200, Traction AA, Temperature, A. The higher the Traction and temperature, say AAA, the lower the tread wear, say 100. There's more involved explanations but for long life street tires you want a high tread wear number like 300. For canyon carving and tracking you want AAA traction and temperature ie sticky and can take the heat. Who cares how long they last?
So what? "Sticky" tires allow you to apply more torque with the engine before the wheels slip, and allow you to apply more torque with the brakes before the wheels "lock up." "Sticky tires help lap times by allowing you to brake later and get on the power sooner. Anti lock brakes and traction control are based on the principal that if the tire is not contacting the pavement without slipping it's going to modulate the power of the engine or the application of the brakes until you're hooked back up to the pavement.
So, to summarize, better brakes, better tires, better traction. Better lap times, safer on the road. You can have good traction and heat resistance and decent wear, but for very high mileage tires you will lose some traction and heat resistance. In other words the tire compound is harder to last longer. No free lunch kids, it's the whole package. And, no matter how good your tires look after, after 5 or 6 years they need to be changed, unless the car is never outside or goes anywhere. (I'm going to take a break now, feel like I've been writing all week.)
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nice thread, Pat. Enjoyed earning a few CE credits at Bullitt University
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